variation, genetics + inheritance

Question 1

define variation

Answer 1

differences in the characteristics of individuals in a population

Question 2

what may be due to the differences in variation?

Answer 2

• genes they have inherited
• conditions in which they have developed (environmental)
• combination of genes and the environment

Question 3

where do variations arise from?

Answer 3

mutations - a change to DNA

Question 4

what is a phenotype

Answer 4

the physical characteristic of an organism

Question 5

how often do mutations occur?

Answer 5

continuously

Question 6

list the 3 sources of variation

Answer 6

• genetics
• environment
• both

Question 7

What does DNA stand for?

Answer 7

deoxyribonucleic acid

Question 8

what is DNA

Answer 8

a polymer - a large molecule made up of repeating subunits

Question 9

what is DNA made up of?

Answer 9

2 strands which spiral around forming a double helix

Question 10

What is DNA called in structures?

Answer 10

chromosomes

Question 11

define a gene

Answer 11

a small section of DNA on a chromosome

Question 12

what does each gene code for?

Answer 12

a particular sequence of amino acids, to make a specific function

Question 13

what is the genome of an organism?

Answer 13

the entire genetic material of that organism

Question 14

list the 4 different nucleotides

Answer 14

CG
AT
GC
TA

Question 15

what are alleles

Answer 15

alternative forms of a gene that code for the different variations of a specific trait

Question 16

describe the process of protein synthesis

Answer 16

• a template is made up of the part of the DNA that codes for a specific protein. Each protein will have a different template
• templates mover from the nucleus to the cytoplasm of the cell
• template then attaches two the ribosome
• carrier molecules attaches to template
• amino acids are joined together to form a protein
• protein folds into its final shape enabling out to do its job

Question 17

what are mutations

Answer 17

rare, random changes that occur in the sequence of DNA bases in a gene or a chromosome

Question 18

what is the name given to the sections of DNA that code for proteins?

Answer 18

exons

Question 19

what is the name given to the sections of DNA that don’t code for proteins?

Answer 19

introns

Question 20

what can a non coding part of DNA do if a mutation occurs?

Answer 20

• prevent some genes from being switched on so the protein is not made
• prevent some genes from being switched off so the protein is made continuously

Question 21

when is a dominant and a recessive allele expressed?

Answer 21

dominant - always expressed, even if one copy is present
recessive - only expressed if 2 copies are present

Question 22

how is polydactyl caused?

Answer 22

by a dominant allele

Question 23

how is cystic fibrosis caused?

Answer 23

by a recessive allele