Welcome to Biology Regents Review… Session 4
Today’s date: ________________
Topics: Punnett squares, protein synthesis, mutations, genetic engineering
Punnett squares:
Cross a dominant homozygous tall plant (TT) with a homozygous recessive short plant (tt). This will be known as the F1
generation.
Genotype: _________________ phenotype: ________________
W = wire haired dog
w = smooth hair dog
Cross a heterozygous wire haired dog with a homozygous smooth haired dog.
Genotype: ____________________________________________
Phenotype ____________________________________________
B = brown
b = silver blue
Brown fur is dominant over silver blue fur in minks. Cross a heterozygous brown male with a heterozygous brown female
in the boxes below.
Take two individuals from the last cross and cross them in the boxes below.
This is known as the F-2 generation. How many brown mink do you have?
How many silver blue mink do you have? _____________
What percentage of the total offspring are brown? ___________
If there are eight mink in the litter, how many of them will be brown? ____
And how many will be silver blue? __________
In cabbage butterflies, yellow color is dominant over white. Set up a key which shows yellow dominant and white
recessive.
If a homozygous yellow butterfly is crossed with a heterozygous yellow butterfly what are the genotype and phenotype of
the resulting offspring?
When dominant red shorthorn cattle are crossed with dominant white shorthorn cattle, the resultant is cattle which show
both the red hair and the white hair. This color is known as roan.
Using R = red and W = white show a cross of a red cow with a roan bull.
In squirrels, the gene for gray fur (G) is dominant over the gene for black fur (g). If 50% of a large litter of squirrels are
gray, the parental cross that produced this litter was most likely
(1) GG x Gg
(2) GG x GG
(3) Gg x gg
(4) gg x gg
Protein synthesis: series of steps that convert the DNA code into an organism’s features.
Steps…
1. Focus on a single gene on a chromosome in the nucleus
2. DNA code gets converted to mRNA code by transcription (C-G, G-C, T-A, A-U)
3. In cytoplasm, mRNA code read as 3-letter codons
4. Codons converted to amino acids by translation at ribosomes
5. Amino acid chains become proteins
6. Proteins determine traits
When cells follow the _________________________ written in the _________________________ to make
_________________________ that determine _________________________.
Where does it occur?
What letters pair together?
Can you make sense of the diagram on the next page?
How do you use the amino acid chart?
Mutations: mistakes made in the copying of the genetic code
Three nucleotide sequences are called “_________________________”
•
Substitution
– One nitrogenous base is replaced with a different one
C
T
A
G
G
A
•
Insertion
– One or more bases are added to a gene
T
A
G
C
C
T
•
Deletion
– One or more bases are deleted from a gene
C
G
A
T
A
G
Name some genetic diseases caused by mutations:
Name some common causes of mutations:
Genetic engineering: improving the DNA of an organism by splicing in sections from other organisms
What are some organisms or substances produced by genetic engineering?
The most clear (and widely used) example of genetic engineering:
1. Gene cut from human _________________________
2. _________________________ DNA cut open
3. Fragments_________________________ together
4. Bacteria_________________________ new DNA as its own
5. Bacteria clone copies of _________________________
6. Bacteria cells follow genetic _________________________
7. _________________________ is made