A
What is a specific DNA sequence that codes for a particular trait?
gene
What are the two types of alleles? Circle the one that always wins when present in a genotype.
1. dominant alleles (always win!)
2. recessive alleles
What genotype(s) express the dominant phenotype? Write the category name and an example.
Homozygous Dominant (AA)
Heterozygous (Aa)
the process by which new gametes are created
meiosis
What are the base-pairing rules for DNA to RNA?
A - ____
G - ____
T - ____
C - ____
DNA RNA
A - U
G - C
T - A
C - G
What are different versions of the same gene called?
alleles
Which allele is only expressed when there are NO dominant alleles present in a genotype?
recessive allele
What genotype(s) expresses the recessive phenotype? Write the category name and an example.
Homozygous Recessive (aa)
What happens during meiosis that helps make gametes genetically unique?
crossing over
What are proteins made of?
amino acids
What are the observable, physical traits of an organism?
phenotype
How many alleles do you inherit from each biological parent for each gene?
Each parent passes on one allele for each gene to their offspring.
1. GG x Gg
2. Gg x Gg
Which set of parents has a higher chance of having offspring with the recessive phenotype? Why?
They each have a recessive allele!
What happens during crossing over?
genes are exchanged between a pair of homologous chromosomes
What are two things that can cause mutations?
1. Errors during DNA replication
2. Mutagens (environmental agents that cause changes to DNA)
What is the combination of alleles an organism has for a particular gene called?
genotype
Red flowers are dominant to purple flowers. What is the genotype(s) of a purple flower? Use R/r.
rr
The only way to show the recessive phenotype is ALL LOWERCASE letters!!
What is the percent chance that the offspring of two heterozygous parents produce an offspring with homozygous recessive traits?
1/4 = 25%
Besides crossing over during meiosis, what else causes genetic variation in a population?
mutations
How do you know if a mutation affects the phenotype?
What is it called when there are differences in DNA sequences between individuals within a population or species that leads to different phenotypes (traits) being seen?
genetic variation/diversity
White feathers are dominant to grey feathers. Cross a heterozygous eagle with a homozygous recessive eagle. What are the genotype and phenotype probabilities for their offspring? Use A/a.
Genotype: Phenotype:
AA = 0/4 = 0% White Feathers = 2/4 = 50%
Aa = 2/4 = 50% Grey Feathers = 2/4 = 50%
aa = 2/4 = 50%
Freckles are dominant to no freckles (F/f). Red eyes are dominant to yellow eyes (R/r). In a dihybrid punnett square, what genotype(s) will show the dominant phenotypes?
FFRR, FFRr, FfRR, FfRr
The parent dogs have brown fur, but some of their puppies have black fur. How is it possible that this different phenotype (trait) is seen in their offspring?
Both parents are heterozygous. The puppies with black fur inherited one recessive allele from each parent.
Original DNA: AAC - GCT - TGA
Mutated DNA: AAC - TCT - TGA
Will the mutated DNA code for the same trait as the original DNA? Why or why not?
Yes, it will code for the same trait because the amino acid sequence is the same!