Biology 23-24
What is crossing over and why is it so important?
Crossing over is in meiosis and the allele trades the same leg to make a copy of the DNA to pass on and then make the traits randomly.
Which of the genotypes in #1 would be hybrids?
Heterozygous
Why does DNA have to replicate? When does this take place in the cell cycle?
It has to replicate so they can divided into two daughter cells in Telophase 1
Phenotype:
is a characteristic or trait on your body
Homozygous
is dominate (AA)
heterozygous:
is recessive (Aa)
What would happen if sex cells divide by mitosis instead of meiosis?
it will be diploid
How many daughter cells are created from meiosis? How many chromosomes do they have compared to the parent cell? Are they identical or different from each other and the parent cell?
2 daughter cells,23 chromosomes, and 2 identical daughter cells.
How many chromosomes do human somatic cells have? Human gametes?
A human has 23 chromosomes, the human gametes are Egg and Sperm
What is the principal enzyme necessary for the addition of nucleotides during DNA replication?
DNA polymerase
Which of the genotypes in #1 would be considered purebred/true-breeding?
Homozygous
What scientists are credited with the discovery of the DNA model that we currently use?
James Watson and Francic Crick
What is the process called that creates haploid gametes from diploid cells
Meiosis
What are the advantages of meiosis over mitosis?
Meiosis makes two identical daughter cells and Mitosis is basically the process of crossing over.
Explain the differences between mitosis and meiosis in terms of processes and differences found in the cells resulting from each type of cell division.
Meiosis processes two identical daughter cells and mitosis processes unique daughter cells.
Draw a molecule of DNA replicating. Label the key components, and be sure to follow the rule of base pairing. (Use this sequence for one of the strands: A T A G C G C AC )
TAT CGC GTG
What important enzyme "unzips" the two DNA strands during replication?
The Helicase
What kind of gamete is formed from the mother? Father? What process brings these gametes together
The egg is formed in the mother and the father is the sperm and then meiosis will bring the gametes together.
What are the 4 nitrogenous bases found in DNA?
Thymine,Adenosine,Cytosine, and Guanine
Describe in detail the overall structure of DNA. In your description, be sure to include what it looks like, what molecules comprise the backbone, etc.
Two strands that come together into a ladder and the shape is a double helix.
Genotype:
an organism
Explain two sources of genetic variation that result from meiosis.
crossing over and assortment
What three molecules make up a nucleotide?
sugar phosphate and Nitrogen bases