Introduction To Genetics

Question 1

What is DNA?

Answer 1

a chemical which carries genetic code

Question 2

What is a gene?

Answer 2

a piece of DNA, or a location on a DNA
- DNA base pairs make up genes which make up
chromosomes

Question 3

What do genes code for?

Answer 3

polypeptides

Question 4

What does DNA stand for?

Answer 4

deoxyribonucleic acid

Question 5

What is the shape of DNA

Answer 5

double helix (like a twisted ladder)

Question 6

What does a dominant gene mean?

Answer 6

it is more common

Question 7

What does a recessive gene mean?

Answer 7

it is less common

Question 8

How was the shape of DNA discovered?

Answer 8

by using x-ray crystallography to discover the double helical shape of DNA

Question 9

Who discovered the double helical shape of DNA?

Answer 9

James Watson and Francis Crick stole photograph 51 from Rosalind Franklin so they got credit for her discovery and won a Nobel Prize

Question 10

What is a chromatid?

Answer 10

one of the two identical halves of a double-stranded chromosome

Question 11

What is a centromere?

Answer 11

the linking structure of a pair of sister chromatids

Question 12

How many pairs of chromosomes do humans have?

Answer 12

23 pairs

46 total

Question 13

What is the exception to the rule of humans having 23 pairs of chromosomes

Answer 13

GAMETES have 23 chromosomes each (the egg has 23 and the sperm has 23) to make up a human which has 46 altogether

Question 14

What makes up the ‘rungs’ of DNA?

Answer 14

bases/amino acids

Question 15

What are the bonds for A, T, C, G

Answer 15

A + T = double bond
C + G = triple bond

Question 16

What are the 2 amino acid pairs that make up DNA?

Answer 16

• Adenine + Thymine (A+T) - double bond, harder to break
• Cytosine + Guanine (C+G) - triple bond, easier to break

Question 17

What is the way in which DNA strands run?

Answer 17

anti-parallel

Question 18

What codes for an amino acid?

Answer 18

a triplet codon (multiple codes can code for one amino acid)

Question 19

What makes up a free nucleotide?

Answer 19

• a base
• a pentose sugar
• a phosphate

Question 20

What causes differences in DNA for different organisms?

Answer 20

differences in the number and arrangement of the amino acids in different organisms

Question 21

How is the free nucleotide positioned on the one side of the DNA compared to the other?

Answer 21

it is upside down to the other side

Question 22

Where are free nucleotides found?

Answer 22

floating around a cell

Question 23

What is a karyotype?

Answer 23

an individual’s complete set of chromosomes in order of size usually

Question 24

What is the male karyotype?

Answer 24

XY

Question 25

What is the female karyotype?

Answer 25

XX

Question 26

Which gender determines the sex of their baby and why?

Answer 26

Males determine the sex of the baby, as either the X sperm or the Y sperm fertilises the X egg.
- if the X sperm (which is a faster swimmer but lives for a shorter amount of time) fertilises the egg it will be female (XX)
- if the Y sperm (which is a slower swimmer but lives for a longer amount of time) fertilises the egg it will be male (XY)

Question 27

What is the chance of your baby being male or female?

Answer 27

it is a 50/50 chance