Meiosis and DNA
Human body cells each have 46 chromosomes in their nuclei. Meiosis is necessary in order to ensure that each gamete produced in the human body has —
23 haploid chromosomes.
The dominant allele F represents green to the recesseive allele blue. What percentage of an offspring will have a heterozygous genotype if one parent is heterozygous and the other is homozygous recessive.
Ff= 50%
In the 1960s the molecular biologist George Streisinger developed the strand-slippage hypothesis. Streisinger noticed that mutations occurred in areas of DNA that contained many repeated sequences. When a strand-slippage error occurs, an insertion mutation can result. How does the insertion mutation affect the DNA?
Nitrogenous bases are added
A segment of DNA that codes for a protein. These are a regulated process.
What is gene?
Nitrogenous bases are located on both strands of the DNA double helix. What is the significance of the nitrogenous bases?
The sequence/order is unique to every individual.
In butterflies the allele for spots (B) is dominant over the allele for no spots. What is the expected percentage of butterflies with spots in offspring of parents that are heterozygous and homozygous dominant?
100% of the butterflies will have spots.
Different types of mutations can occur in DNA. Which mutation has occurred below?
A T T G C A -----------> A T A T G C A
Frameshift: Insertion
The phase where a cell spends 90 percent of its time in the first three phases of the cycle.
What is interphase?
Genetic variation is possible because recombinant chromosomes are produced during this process.
Crossing over.
Sickle cell is an autosomal recessive condition r. A female with sickle cell mates with a male that is homozygous dominant for the sickle cell trait. What are the expected genotypic ratios?
4 Rr: RR 0: rr 0
A mutation in which types of cells would only affect the organism and not future generations?
A. Sperm cell and egg cell
B. Nerve cell and brain cell
C. Sperm cell and lung cell
D. Egg cell and liver cell
B. Nerve cell and brain cell
The uncontrolled growth of cells or division.
What is cancer?
Perform transcription on the following:
A G C A T C G
mRNA= U C G U A G C
FOIL the following genotype:
G G T t
F: GT
O: Gt
I: GT
L: Gt
Which of the following is the purpose of translation?
A. To assemble nucleotides in an mRNA chain along a DNA template
B. To translate the genetic code into a specific sequence of amino acids
C. To synthesize amino acids used to unzip strands of DNA and copy the genetic code
D. To replicate the DNA of an organism before cell division
B. To translate the genetic code into a specific sequence of amino acids
The process during cell division in which the nucleus of a cell is divided into two nuclei.
What is mitosis?
The process of the tRNA assembling the correct amino acids in a chain.
Translation
Solve the following: A male rabbit with the genotype GGbb is crossed with a female rabbit with the genotype ggBb. Determine the phenotypes and proportions (fractions) in the offspring.
8/16 GgBb
8/16 Ggbb
Different types of mutations can occur in DNA. The following mutation occurred and caused the amino acid to change. Which mutation has occurred?
A T T G C A -----------> A T T G C G
What is Point mutation: Substitution
The sequence of nitrogenous bases in DNA varies widely. The sequence of the bases in DNA is most important for which of the following?
A.The sequence creates a chain of nucleotides that become the instructions for mutations.
B. Providing the instructions for the traits of an organism.
B. Providing the instructions for the traits of an organism.