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Chapter 4: Genetics: the Science of Heredity

This is on section 1-4 of Chapter 4.
STUDY
PLAY
Heredity
passing of physical characteristics from parents to offspring.
Gregor Mendel
Father of Genetics; formed their foundation
trait
Each different form of a characteristic
Genetics
scientific study of heredity
fertilization
when egg and sperm join
purebred organism
offspring of many generations that have the same trait.
gene
factors that control a trait
alleles
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.
hybrid
organism that hastwo different alleles for a trait
probability
number that describes how likely it is that an event will occur.
punnett square
a chart that shows all the possible combinations of alleles that can result from a genetic cross
phenotype
visible traits or physical appearance
genotype
genetic makeup
codominance
alleles are neither dominant nor recessive so they are both expressed in offspring
meiosis
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.
mutation
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.

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