How can we help?

You can also find more resources in our Help Center.

Chapter 4: Genetics: the Science of Heredity

This is on section 1-4 of Chapter 4.
passing of physical characteristics from parents to offspring.
Gregor Mendel
Father of Genetics; formed their foundation
Each different form of a characteristic
scientific study of heredity
when egg and sperm join
purebred organism
offspring of many generations that have the same trait.
factors that control a trait
differetn forms of a gene
How are an organism's traits controlled?
They are controlled by the alleles inherited from their parents.
Dominant allele
One whose trait always shows up in the organism when the allele is present.
recessive allele
hidden whenever the dominant allele is present.
organism that hastwo different alleles for a trait
punnett square
visible traits or physical appearance
genetic makeup
alleles are neither dominant nor recessive so they are both expressed in offspring
process when the number of chromosomes is reduced by half to form sex cells
Stage: Before Meiosis
each chromosome in the parents are copied
Stage: Meiosis 1
chromosome pairs move to the center, separate, and pull the cell intro two cells. With half the number of chromosomes in each.
Stage: meiosis 2
The two new cells move and split into 4.
Stage: Meiosis end
four sex cells have been produced, with only half the number of chromosomes that the parent cell had at the beginning.
Four nitrogen bases
adenine, thymine, guanine, and cytosine
Genetic code
formeed by nitrogen bases along a gene. specifies the type of protein produced.
Protein syntheses
production of proteins. Uses the info from a gene on a chromosome to produce a specific protein. takes place in the cytoplasm of a cell.
Differences between RNA and DNA
RNA: has one strand, uses Uracil, and has Ribose. DNA: has 2 strands, uses thymine, and has Deoxyribose
Messenger RNA
copies the coded message from the DNA in the nucleus and carries it to the ribosome
Tranfer RNA
Type of RNA that transports amino acids to ribosomes. Reads the message
Trans. the code: 1
DNA molecule unzips between the bases to allow the RNA strand to match up and transfer genetic info from the DNA to the RNA.
Trans. the code: 2
Messenger RNA leaves the nucleus and attaches to a ribosome. The RNA provides the code to make a protein molecle.
Trans. the code: 3
Transfer RNA attaches to the messenger RNA. Transfer RNA "read" the message by pairing up to the messenger RNA. Messenger RNA carries amino acids that link in a chain.
Trans the code: 4
Protein molecule grows as each transfer RNA put the amino acid along the chain. The chain grows until they have enough and the the ribosome releases the completed protein.
change in gene or chromosome. can cause a cell to produce an incorrect protein.
Types of mutation
deletion, addition, substitution
Effects of mutations
can be harmful or helpful, depends on environment.

Flickr Creative Commons Images

Click to see the original works with their full license.