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405 Cards in this Set

  • Front
  • Back
a package of nucleic acid wrapped in a protein coat
a virus that infects bacteria (phage)
deoxyribonucleic acid. the molecule that stores genetic information
makes up DNA. Made up of three parts: a sugar, a phosphate group and a nitrogenous base.
nitrogenous base
a single or double ring of carbon and nitrogen atoms with functional groups
nitrogenous bases with single rings
nitrogenous bases with double rings
double helix
DNA molecule's twisting shape
Adenine pairs with...
guanine pairs with...
DNA replication
the process of copying the DNA molecule. During the process, the two strands seperate. Each strand is used as a template. Nucleotides are added to the new strand, according to the rules of base pairing.
DNA polymerases
enzymes from the bods between nucleotides of the new DNA strand
the process of when the DNA strand is converted to the form of a single-stranded RNA
ribonucleic acid. a nucleic acid with the sugar ribose rather than deoxyribose.
the RNA moves to the cytoplasm and cinverts the nucleic sequence into a sequence of amino acids
three-based sequence, codes for one amino acid - the order of codons in the RNA determines the order in which the amino acids will be put together to form a polypeptide
messenger RNA
(mRNA) transcribed from DNA molecule
RNA polymerase
joins the RNA nucleoides together during transcription
molecules within mRNA that do not code for amino acids
RNA splicing
removes the intorns and joins the coding regions
coding regions of mRNA
transfer RNA
(tRNA) a molecule with an amino acid binding site at one end and a three-base anticodon at the other end
a sequence that is complementary to a codon in the mRNA. The tRNA anicodon bids to the mRNA codon, bringing an amino acid in position to be added to the polypeptide.
ribosomal RNA
makes up ribosome of cell
a change in the nucleotide sequence of DNA. substitutions: one nucleotide is replaced by another. Insertions/deletions: one or more nucleotides are added or removed from gene
a physical or chemical agent that causes a mutation.
is an organism's complete set of DNA. "supercoil"
the DNA is wrapped tightly around these small proteins
Human Genome Project
provided a rough draft of the human genome's entire sequence (can help show evolution, identify diseases)
Trisomy 21
a condition in which a person has thre number 21 chromosomes. Results in symptoms of Down syndrome
Down Syndrome
symptoms: facial features, below-average height, heart defects, varying degree of mental disability, lifetime is shorter than average
a pair of homologous chromosomes or sister chromatids fail to seperate during meiosis
occurs when a part of a chromosome is repeated and can cause other disorders
occurs whn part of a chromosome is reversed
occurs when a portion of a chromosome attaches to a non-homologous chromosome
"jumping genes". single genes changing their position on the chromosome or moving to another chromosome entirely.
traces the occurence of a trait in a family
an individual with one copy of the allele for a recessive disorder who does not show symptoms
sex-linked disorder...
color-blindness(mostly males)
recessive disorders...
albinism (not life-threatening)
Tay-Sachs disease and cystic fibrosis (life-threatening)
genetic counselor
a individual trained to collect and interpret family histories of genetic disorders
growth factors
one class of genes codes for proteins which start the process of cell division
tumor-suppressor genes
the other class of genes that produce proteins that stop cell division when a cell's DNA is damaged
this is when a gene has become a cancer-causing gene because of mutations to growth factors or tumor-suppressor genes
the use of organisms to perform tasks for humans
recombinant DNA
to combine genes from different organisms or species
small, circular DNA molecules that are seperate from the much larger bacterial chromosome within many bacteria
restriction enzyme
"cuts" a DNA molecules into fragments at specific points
genomic library
a complete collection of cloned DNA fragments from an organism
nucleic acid probe
a molecule that has been labeled with radioactivity, making it easy to detect
genetically modified organism
(GMO) any organism that has acquired one or more genes by artificial means
a GMO that has recieved new genetic material came from a different species
polymerase chain reaction
(PCR) is a technique that makes billions of identical DNA molecules in just a few hours-->used to produce large enough samples of DNA for further analysis
gel electrophoresis
a technique for sorting DNA fragments by length (shorter fragments pass more quickly through electrically charged gel than longer fragments)
genetic markers
particular stretches of DNA that vary from person to person
DNA fingerprint
produced by each person's unique pattern of banding of DNA fragments
a cluster of genes, along with its two control sequences
one control sequence that is a binding site for an enzyme needed in DNA transcription
the other control sequence that switches the promotor on and off
a protein tht turns the operator on and off by binding to it
gene expression
the transcription and translation of genes into proteins
transcription factors
proteins that regulate promoter sequences of some genes
cellular differentiation
individual cells become more specialized in structure and function as the organism develops
stem cells
cells that remian able to differentiate into various other types of cells
homeotic genes
master control genes that produce proteins that regualte the expression of other genes
all of the changes that have transformed life over an immense time
an inherited characteristic that improves an organism's ability to survive and reproduce in a particular environment
descent with modification
specis living on the Earth today descended from earlier species
natural selection
the process by which individuals with inherited characteristics well-suited to the environment leave more offspring on average than do other individuals
Charles Darwin
sailed around the wrold on the Beagle. His observations of variation in birds and other prganisms led him to suggest that species change as they adapt to their changing environments=theory of evolution (1) descent with modification (2) natural selection
are preserved remains or markings left by organisms that lived in the past
fossil record
the collection of fossils recorded in rock layers over time
species that no longer exist
homologous structures
similar structures among related species
vestigial structures
homologous structures that have a major function in one species but not in a related species
differences among members of the same species
artificial selection
selective breeding of plants and animals to produce offspring with traits that humans value
gene pool
consists of all the alleles, or different forms of genes, in all the individuals in a population
Hardy-Weinberg equilibrium
populations that do not undergo change int heir gene pools-->not presently evolving
genetic drift
a change in gene pool due to chance
gene flow
the exchange of genes with another population
the contribution that an individual makes to the gene pool of the next generation compared to the contribution of other individuals
drugs that kill or slow the growth of bacteria
biological species concept
defines a species as a population or group of populations whose members have the ability to breed with one another in nature and produce fertile offspring
the origin of new species
major evolutionary changes such as speciation (exinction of species, evolution of new features i.e. wings)
repreoductive isolation
the inability of different species to interbreed
geographic isolation
Occurs when a population becomes seperated from the rest of the species due to geographic change or movement to an isolated place.
adaptive radiation
when populations of a new species evolve adaptions to a variety of different environment and form a diverse new species
punctuated equilibrium
long periods of little change are broken by shorter times od more rapid change
the study of how multicellular organisms develop from fertilized eggs to adults
radiometric dating
method based on the amount of radioactive isotopes in a fossil
the time i takes 50% of the original sample to decay
geologic time scale
organizes Earth's history into Precambrian, Paleozoic, Mesozoic and Cenozoic eras.
continental drift
cause of changes in life forms the movement of Earth's ccontinents on large plates of crust
mass extinction
most often occurs at the end of eras. Provides surviving organisms new oppottunities and leads to adaptive radiation
a branch of biology that involves identification, naming, and classification of species. Assigns universal scientific name to each known species. Orgaizes diversity of life by classifying species into larger groups of related secies
two-part name created by Carolus Linnaeus for each species. helps in taxonomy.
phylogenetic tree
a diagram that shows hypothesized evolutionary relationships
convergent evolution
a process in which unrelated species from similar environemtn have adaptions that seem very similar
analogous structures
similar adaptions of convergent evolution
derived characters
homologous charcteristics that unite a group of organisms
phylogenetic trees constructed froma series of two-way branch points. Bacteria, Archea, Eukarya
thin layers of sediment pressed tightly together
prokaryotes, may of which live in some of the most extreme conditions of the Earth. Has introns (noncoding portions of genes)
prokaryotes, introns absent. Bacterial wall contains polymer peptidoglycan
three basic shapes of bacteria are:
- spherical bacteria (cocci)
- rod-shaped bacteria (bacilli)
- spiral-shaped bacteria (spirochetes)
two types of bacteria cell walls are:
- peptidoglycan
- peptidoglycan and additional outer membrane
binary fission
simple cell division of prokaryotes. Produces cells that are gentically identical
Genetic mixing or recombination can happen in three ways:
- transformation
- conjugation
- transduction
bacteria pick up pieces of DNA from the environment
two bacterial cells tomproarily join and transfer genetic material
viruses tha infect bacteria carry genes from one cell and inject them into another
"resting cells" survive harsh conditions
a group of bacteria that generates oxygen as a waste product of photosynthesis
the use of organisms to remove pollutants from water, air and soil
bacteria and other microorganisms that cause disease
lytic cycle
a phage attacxhes tot he host cell and injects its DNA into the host-->the host cell makes copies of viral DNA and viral p[roteins-->bursts open releases produced viruses
lysogenic cycle
a phage injects its genes into the host cell, and the viral DNA adds itself directly to the host cell's DNA. When bacterium reproduces, it copies viral DNA.
a virus that reverses the usual DNA-to-RNA flow of genetic information (HIV)
is a deactivated variety or small prece of a pathogen that causes the immune system to defend against the actual pathogen
the study of an organisms' structure
the study of what structures do and how they do it- their function
a group of many similar cells that work together and perform a specific function
several tissues that together perform a soecific task
organ system
multiple organs that together perform a necessary body function
body's organ systems:
circulatory, integumentary, skeletal, muscular, dgestive, nervous, respiratory, endocrine, lymphatic, immune, excretory, and reproductive
epithelial tissue
covers the surface of the body and lines the internal organs
connective tissue
hods together and supports other tissues (cushions, insulates, and connects organs)
nervous tissue
forms the communication system of the body
three types of tissues:
epithelial, connective, nervous
three types of muscle tissue:
skeletal, cardiac, smooth
skeletal muscles
made of skeletal muscle tissue, are attached to bones and enable various parts of the body to move
cardiac muscles
made up of cardiac muscle tissue and are found in the heart (involuntary)
smooth muscles
made of smooth muscle tissue and are found in the digestive system and most other organs (involuntary)
when the body protects itself from chnage in the outside environment and provides a stable internal environment
chemical signals that trale through the bloodstreamto other parts of the body where they trigger particular responses (help maintain homeostasis)
interstitial fluid
solution that fills the gaps between cells
integumentary system
the body's outer covering (the skin)
the outermost layer of skin (dead epithelial cells that flake off on top layer, bottom layer contains cells that produce melanin)
a protein the gives skin its color
lies beneath epidermis and made of mostly connective tissue (strength and elasticity, hair follicles, oil/sweat glands, muscles, nerves and blood vessels)
a issue layer beneath dermis that contains fat-storing cells and blood vessels (made up of protein called keratin)
small, flat bones that make up the backbone
a type of connective tissue that is softer than bone
specialized tissues within many bones( yellow: stored fat that reserves energy. red: cells that develop into red blood cells)
where one bone meets another bone(immovable=skull)
fibrous connective tissues that hold togeter bones in movable joints
inflammation of the joints
bones become thinner and break easily
a connective tissue that attaches a muscle and a bone
muscle fiber
a single long muscle cell that contains many nuclei
smaller fibers inside a muscle fiber
bundlesof smaller fibers consisting in a single myofibril
protein that make up thin filaments
protein that makes up thick filaments
central nervous system
(CNS) includes the brain and spinal cord, processes information
peripheral nervous sytem (PNS)
includes all the rest of the nervous system tissue
recieved by PNS when sensory input occurs
sensory receptors
detect stimuli
sensory neurons
detect stimuli
interpret sensory information
motor neurons
carry away response from CNS (motor output)
a rapid and automatic response
recieve sinals for neuron and carry them toward cell body
longer fiber tjay carries signals away from cell body and towards other cells
myelin sheath
cover axons
uncovered spaces that lie between section of myelin sheath. allow singlas to travel quickly by jumping from node to node
resting potential
the inside of a nerve cell is negative in electrical charge compared to the outside. greater concetration of sodium ions (Na+) outside than inside the cell
the inside of the cell becomes positive compared to the outside
when neuron is stimulted to a certain level, additional Na+ rushes into the cell causing greaer depolarization
action potential
the stronger depolarization from threshold is the start of a nerve signal
synaptic cleft
the space between neurns that the chemical signal is carried
they are released at the end of the axon and cross the synaptic cleft to the next neuron
somatic nervous system
carries signals from CNS to skeletal muscles (voluntary actions)
autonomic nervous system
carries signals from CNS to organs and glands (involuntary actions)
sympathetic division (of the autonomic nervous system)
increases the level of activity in the body (except for digestion)
parasympathetic division (of the autonomic nervous system)
calms the body and returns it to regular function (increase digestion)
the largest and most complex part of the brain
corpus callosum
thick band of nerve fibers that connect the two hemispheres
cerebral cortex
the outside part of the cerebrum
coordinaes body movements
filters all the sensory and motor information traveling to and from the brai. controls sleep and breathing
filters information traveling to and from cerebral cortex. Blocks some signals and increases others
helps regulate body temperature, blood pressure, hunger, thirst, emotions
the ability to store and recall information from past experiences
limbic system
the region of the brain where connectionsbetween memory, emtions and senses are made.
awareness of sensory information
meaningful interpretation of sensory information
clear area on surface of eye that light enters through
dark opening in the iris
colored part of eye
inner surface of the back of the eye
distinguish colors
sensitive to dim light
auditory canal
sound waves channeled through this to the eardrum
sheet of tissue that vibrates when sound waves strike it
a coiled tube that contains fluid and is lined with tiny hairs. Sound wave vibration move the fluid which thn move the hair which then send action potentials to the brain
auditory tube
lets air move between inner ear and throat
more and more of the drug is needed to produce te smae effect
an uncontrollable dependance on a drug
symptoms of when the drug is not taken
increase CNS activity and include caffeine, nicotine, and cocaine
decrease CNS activity. may interfere with coordination and judgement. include: alcohol, tranquilizers, marijuana
made from the opium poppy and act as natural brain chemicals and include: morphine and heroine. produce feelings of joy and block pain signals
are substances such as LSD that cause user to see, hear and percieve things that do not exist
is a drug that is a stimulkant and a hallucinogen
aerosols that produce vapors that have mindaltering effects
the process of mhow your body obtains raw materials from food
four stages of nutrition:
ingestion, digestion, absorption, and elimination
the act of eating or drinking. Occurs in the mouth
the process of breaking food down into molecule small enough for the body to absorb. mechanical: chewing, churning. chemical: breaks down chemical bonds within larger molecules
cells take up the snall molecules
undigested material passes out of the bidy as waste
alimentary canal
tube in which digestion occurs
six organs that make up the alimentary canal:
a liquid containing digestive enzymes which begin the chemical digestion
chewed clump of food that the tongue pushes down the throat and enters the stomach
a stretchy muscular sac. Secretes digestive juices and acids, which continue chemical digestion. Muscles also create a churning motion that completes mechanicaldigestion
liguid food created in stomach from bolus
small intestine
a long tube where chemical digestion is completed and most nutrients are absorbed
prodces a digestive juice called BILE that helps chemical digestion
sac-like structure that stores bile
secretes enzymes into the small intestine that help complete chemical digestion (similar to liver)
villi (villus)
small, finger-like projections found in small intestine that increase the surface are. Filled with lympth vessels and blood vessels that absorb nutrients and carry them to cells throughout the body
large intestine
organ in which undigested material passes and which water is absorbed into the body
undigested food material and other waste products in the large intestine
movement which allows feces to travel through the large intestine
essential nutrients
materials that must be ingested because your cells cannot make them from other molecules
Food Guide Pyramid
shows the recommended daily number of servings of different types of food
a diet lacking one or more essential nutrients
a diet lacking enough Calories
the condition of being seriosuly overweight (risk of diabetes)
a psycological condition in which an eating disorder is formed and as a result, starve themselves and become extremely thin
another psycological conditionin which an eating disorder is formed and as a reslt, binge (eat too much) and purge (rid themselves of the food by vomiting or using laxatives)
a type of connective tissue made up of cells and liquid parts
a muscular organ with four hollow chambers that pump blood throughout the body
three types of blood vessels:
capillaries, veins, arteries
are microscopic vessels through which nutrients, oxygen, and wastes move beween blood and interstitial fluid
are thick-walled vessels that carry blood from heart to capillaries. thicker walls than capillaries
are vessels that carry blood from capillaries to the heart (oxygen-depleted blood). Has valves
fluid that reenters capillary at the vein end of the capillary-->the rest of the fluid is collected by vessels that make up the lmphatic system-->once inside the lymphatic system near the heart, this fluid is called lymph. Fluid is reused
pulmonary circuit
carries blood between heart and lungs
systemic circuit
carries blood between the heart and the rest of the body
large artery in which oxygen-rich blood leaves the heart
atria (atrium)
the two upper chambers of the heart that recieve blood returning to the heart
the two lower chambers that the atria pump blood into. Ventricles pump blood ut of the heart
the flaps of tissue on the heart that prevent blood from flowing backward
the region of the heart that sends out electrical impulses that make the atria contract
AV node
another region in which the impulses from the pacemakers cause the ventricles to contract
systolic pressure
the first number of bloog pressure that is produced when the ventricles contract
diastolic pressure
the second number that is produced when the heart relaxes
a solution of water, dissolved salts, proteins and other substances. makes up 55% of blood volume
red blood cells (RBC)
carry oxygen from the lungs to all the tissues of the body. Contains hemoglobin that attracts oxygen
a rotein that stores oxygen for delivery to cells
white blood cells
leukocytes. Fight infection and prevent the growth of cancer
blood cells that are responsible for blood clotting. Release clotting factors that form protein, fibrin. Fibrin then traps platelets and blood cells, forming a clot
deposits of fat and minerals
cardiovascular disease
illness of the heart and/or blood vessels caused by plaque build up
narrowing of arteries by plaque buildup
heart attack
a caused by a blood clot that blocks an artery
when plaque buildup hardens over time-->increases blood pressure
a person with blood pressure of 140/90 or higher for and extended period of time
a blood clot in an artery going to the brain
name eight steps in the process of retrieving oxygen:
nose/mouth, oharynx, larynx, trachea, bronchi, bronchioles, alveoli
a chamber in the upper throat
a flap of tisue that covers the air pathway and prevents water or food from entering
voice box
red blood cells (RBC)
a rotein that stores oxygen for delivery to cells
white blood cells
leukocytes. Fight infection and prevent the growth of cancer
deposits of fat and minerals
cardiovascular disease
narrowing of arteries by plaque buildup
heart attack
a caused by a blood clot that blocks an artery
when plaque buildup hardens over time-->increases blood pressure
a blood clot in an artery going to the brain
name eight steps in the process of retrieving oxygen:
a chamber in the upper throat
voice box
red blood cells (RBC)
a rotein that stores oxygen for delivery to cells
white blood cells
leukocytes. Fight infection and prevent the growth of cancer
deposits of fat and minerals
cardiovascular disease
narrowing of arteries by plaque buildup
heart attack
a caused by a blood clot that blocks an artery
when plaque buildup hardens over time-->increases blood pressure
a blood clot in an artery going to the brain
name eight steps in the process of retrieving oxygen:
a chamber in the upper throat
voice box
air tubes branch from trachea to lungs
smaller air tubes that branch from bronchi
air sacs at the end of each bronchiole
a sheet of muscle that when you inhale, contracts and chest expands, causing air to rush into lungs. and when you exhale, the diaphragm relaxes as the chest contracts, causing air to rush out of the lungs
what are two diseases caused by smoking?
lung cancer and emphysema
a disease that develops when tobacco smoke causes the walls of the alveoli to lose their flexibilty--shortage of breath
infectious diseases
disease caused by pathogens
the germ theory of disease
states that infectious disease is caused by pathogens that can spread disease from one organism to another
what are the ways infectious dieases can be spread?
physical contact, inhaling, contaminated water or food, sexual contact, animals
nonspecific defenses
barriers that do not distinguish one invader from another.
first line of defense
skin: phyisical barrier, chemical: sweat/saliva, tears that contain enzyme lysosome
second line of defense
nonspecific. certain white blood cells and inflammatory response
way in which certain white blood cells destroy microorganisms--engulfing or swallowing them
prtein that prevents viruses from reproducing
inflammatory response
accompanied by redness, heat, swelling and pain. mast cells release histamine
released by mast cells and cause nearby blood vessels to expand, allowing more blood to flow to injured tissues
third line of defense
immune system: recognizes and defends against soecific pathogens, cancer cells, and certain chemicals
your body is resistant to the pathogen that causes a specific disease
a large molecule that cause immune response
a protein found on the surface of a certain white blood cells or blood plasma. Attachess to an antigen molecule with matching shape and destroys invader/makes it harmless
two types of white blood cells:
B cells and T cells
B cells
play a key role in humoral immunity
T cells
play a major role in cell-mediated immunity
humoral immunity
specific immunity provided by B cells that produce antibodies that circulate in body fluids-->antigen binds to antibody-->B cells make millions of clones-->develop into plasmma cells
plasma cells
produce antibodies to antigen
cell-mediated immunity
T cells attacking body cells that are infected with a pathogen-->antigens attach to antibody on T cell -->clones itself-->cytotoxic T cells
cytotix T cells
attack cells infected with pathogen, destroy cancer cells
helper T cell
secretes chemicals that help T and B cells to respond to pathogens
memory cells
make clones that can fight the same pathogen if it enters the body again
active immunity
whenever the body produces antibodies against infection
passive immunity
recieves antibodies for a particular disease from another source (lasts for a short amount of time)
an abnormal reaction to non-harmful antigen. mast cells produce histamines-->inflammatory response
autoimmune disease
condition in which the immune system attacks some of the body's own molecules
disease caused by HIV virus-->destorys helper T cells, body becomes unable to defend itself
negative feedback
a change that triggers a response that counteracts the change
ammonia and carbon dioxide formed within liver
removal of nitrogen-containing wastes (urea) from body
trigger many of the responses that maintain homeostasis. Regulate blood presssure, heart rate, digestion, other body functions
endocrine glands
organs that secrete hormones
target cells
certain cells that the hormones only affect
main organs of the excretory system. Filter blood and produce urine
a liquid made of ater, urea, and other waste products
tube which carries urine from kidneys to urinary bladder
urinary bladder
a sac that stores urine until it leaves the body
tube in which urine leaves the body
tiny tubes within kidneys that filter blood and excrete urine in a four-step process
what is the four-step process that the nephrons conduct?
- filtration, reabsorption, secretion, excretion
a tiny ball of capillaries that houses filtration
fluid forced through capillary walls
water and dissolved nutrients are reabsorbed from the filtrate into the blood
certain substances are removed from the blood and added to the filtrate
urine leaves the body
hormone produced by hypothalamus when water level falls below normal and stimulates kidneys to produce more concentrated urine-->less water in urine
patient's blood is pumped through a machine that functions like a kidney in removing wastes (another treatment is kidney transplant)
liver changes excss glucose to glycogen -->stores it and is broken down into gluccose whenever needed
liver diease that is often caused by a virus. spread through sexual contact and sharing drug needles
occurs when liver is so scarred that it can no longer function effectively. symptoms: internal bleeding, difficulty digesting fats
steroid hormones
can cross plasma membrane and influence geness and production of proteins
nonsteroid hormones
cannot cross plasma membranes. influence cell activites indirectly through other molecules inside cell (secondary messengers)
make hormones that direct activities of many endocrine glands (pituaitary gland)
releasing hormones
stimulate pituitary to secrete its own hormones
pituitary gland
secretes hormones that influence other glands and body functions
secretes hormones that affect almost every tissue in the body. Hleps maintain normal blood pressure, heart rate, digestion, and reproductive functions
secretes two hormones that regulate amount of glucose in body: insulin and glucogen
decreases blood glucose by increasing the amount of glucose that eneters body cells
increases blood glucose by stimulating liver cells to break ddown glycogen into glucose
a disease in which body cells are unable to absorb glucose from the blood
adrenal glands
produce hormones in response to stress. some hormones are fast-acting and have a short-term effect
stimulates faster breathing and heart rate
provide slower, longer-acting response to stress
what are the female reprodductive structures?
- ovaries, oviducts, uterus and vagina
two organs where eggs are produced
cluster of cells that contain each egg
a tube that openss near each ovary
hollow organ that protects the developing baby
connects uterus to the vagina
flexible organ that openss to the outside
what are the male reproductive structures?
- testes, scrotum, epididymis, vas deferns, penis
two organs in which sperm begins development
sac-like structure that contains testes
a coiled tube attached to each of the testes where sperm completes its development
vas deferens
where muscle contractions are forced through ejaculation
made of tissue that fills with blood-->causing an erection
when the egg is released from the ovary once a month
mature egg is formed by being penetrated by a sperm
ovarian cycle
refers to changes in the ovaries that occur in a mature female each month. controlled by hormones
menstrual cycle
refers to changes in uterus. controlled by hormones
lining of the uterus
FSH (follicle stimulating hormone)
released by pituitary gland signaled by hypothalamus when estrogen levels are low-->FSH stimulates a follicle and its egg to mature
when low estrogen levels cause lining of uterus (endometrium) to break down and shed
corpus luteum
when LH (luteinizing hormone) stimulates the follicle to release its egg-->which secretes estrogen and progesterone. structure is then called corpus luteum
FSH and LH in males:
FSH stimulates testes to produce sperm. LH stimulates testes to produce testosterone
IN MALES. hormone that helps stimulate sperm production in the testes
estrogen and progesterone
IN FEMALES. hormones that stimulate he endometrium to prepare for pregnancy. (if pregnancy does not occur, corpus luteum breaks down and stops secreting hormones-->falling estrogen levels start cycle over again)
occurs when egg and sperm cells join
fertilized egg cell
when the egg starts dividing rapidly after 36 hours of fertilization
zygote becomess embryo once cleavage begins and until first body structure appears
hollow ball of cells thaat cleavage produces
outer layer of blastocyst (inner layer eventually forms organism)
the imbedding of the blastocyst in the endometrium
twins (fraternal)
two embryos
identical twins
one embryo splitting intwo