Intro to human genetics

Question 1

Width of DNA?

Answer 1

2nm

Question 2

Charge of phosphate group?

Answer 2

Negatively charged

Question 3

How many H-bonds between Thymine and Adenine?

Answer 3

2

Question 4

How many H-bonds between Guanine and Cytosine?

Answer 4

3

Question 5

how does the sugar phosphate backbone bond?

Answer 5

5’ phosphate bonds to 3’ ribose Carbon

Question 6

How many histones make up a nucleosome?

Answer 6

8

Question 7

How wide is a nucleosome?

Answer 7

11nm

Question 8

How many times does DNA wrap around histones?

Answer 8

1.65 times (210 base pairs)

Question 9

How wide are nucleosomes once folded together into a fibre?

Answer 9

30nm

Question 10

What are the length of the loops formed from nucleosome fibres?

Answer 10

300nm

Question 11

What are the light areas of a nucleus called? What are some traits of this area?

Answer 11

Euchromatin.
DNA more accessible.
Where active genes are.

Question 12

What are the dark areas of a nucleus called? What are some traits of this area?

Answer 12

Heterochromatin.
Less accessible DNA (More packaged).
Less gene transcription occurring.

Question 13

What are karyotypes?

Answer 13

An individuals complete set of chromosomes.

Question 14

How are karyotypes dyed to be visible?

Answer 14

G-banding.
Giesma is applied on a cell arrested in metaphase.

Question 15

What is the purpose of G-banding?

Answer 15

Identify abnormalities.
Identify where chromosomal translocations occur.

Question 16

What is a Mendelian trait?

Answer 16

A trait controlled by a single locus in an inheritance pattern

Question 17

What is a gene?

Answer 17

Unit of inheritance transferred from parent to offspring.
Determines a characteristic of offspring.

Question 18

What is the law of segregation?

Answer 18

During gamete formation.
Alleles from each gene segregate.
So gametes only carry one allele for each gene.

Question 19

What is the law of independent assortment?

Answer 19

Genes from different traits can segregate independently during the formation of gametes.

Question 20

What is the law of dominance?

Answer 20

Some alleles dominant, some recessive.
An organism with at least one dominant allele, will display the dominant phenotype.

Question 21

What is meant by X-linked?

Answer 21

Gene only on X chromosome.