Genetics

Question 1

What is the difference between chromatin and chromosomes? How are they related?

Answer 1

Chromatin is unwound DNA and proteins that make up chromosomes

Question 2

Describe the make-up of a DNA molecule.

Answer 2

DNA is made up of molecules called nucleotides. Each nucleotide contains a phosphate group, a sugar group and a nitrogen base. The four types of nitrogen bases are adenine (A), thymine (T), guanine (G) and cytosine (C).

Question 3

In comparison, how much of a cell’s life is spent in interphase vs mitosis?

Answer 3

3/4 or 78% is spent in interphase

Question 4

How does mitosis and cytokenesis differ in plants and animals?

Answer 4

Animal cells split while plant cells have cell walls form in the middle.

Animal cells have centrioles, plant cells don’t

Plant cells only divide in a special region called the meristems

Question 5

What is the end result of meiotic division?

Answer 5

One diploid cell -> 4 haploid cells

Question 6

What are homologous chromosomes?

Answer 6

Homologous chromosomes are similiar but not identical. Each carries the same genes in the same order, but the alleles for each trait may not be the same. 1 chromosome comes from mom, the other comes from dad

Question 7

What is meant by the terms haploid (N), and diploid (2N).

Answer 7

Haploid cells have one set of chromosomes, n. Diploid cells have 2 sets of chromosomes, 2n. Sex cells are haploid

Question 8

Explain how sex is inherited.

Answer 8

Women carry X chromosomes, Men carry X and Y chromosomes, The child can be XX or XY

Question 9

What is crossing over? What stage of meiosis does it take place in, and why is it
important?

Answer 9

Crossing over is the exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring.

It occurs between prophase I and Metaphase I

Question 10

What is random assortment?

Answer 10

Pairs of similar chromosomes are called homologous chromosomes. During meiosis, the pairs of homologous chromosome are divided in half to form haploid cells, and this separation, or assortment, of homologous chromosomes is random.

Question 11

What is non-disjunction, and what are some of the problems it can cause?

Answer 11

Nondisjunction refers to a pair of chromosomes not fully separated during meiosis resulting in the gamete having an extra chromosome or none at all

Monosomy ( turners syndrome) and trisomy (down syndrome) are side effects

Question 12

How is the color blind gene inherited?

Answer 12

Colour blindness is a recessive mutation on the X chromosome, this means that for a son to be colour blind he needs a mutated X from mom but a daughter needs a mutated X from mom and dad

Question 13

What is genetic testing? Give some examples of things that can be tested for.

Answer 13

Testing a persons genetics for mutations/abnormalities

Question 14

Define the following terms: genetics, gene, allele, dominant allele, recessive allele,

Answer 14

Genetics - Genetics is the study of genes, genetic variation, and heredity in living organisms.
Gene - Segment of DNA which controls the development of one or more traits
Allele - pairs or series of genes on a chromosome that determine the hereditary characteristics
Dominant Allele - Masks a recessive allele (upper case) Xx shows X
Recessive Allele - Covered by a dominant allele (lower case) xx shows x but Xx shows X

Question 15

Explain how sex is inherited.

Answer 15

Women carry X chromosomes, Men carry X and Y chromosomes, The child can be XX or XY

Question 16

Explain how blood groups are inherited.

Answer 16

A and B are co dominant and O is recessive

A can be Ia Ia or i i
B can be Ib Ib or i i
AB is Ia Ib
O is i i