genetics - inheritance

Question 1

define mutation

Answer 1

change in order of bases in genetic code

Question 2

what two different types of mutations can occur?

Answer 2

• change in amount of DNA (chromosome mutation)
• change in structure / arrangement of DNA (gene mutation)

Question 3

in what organisms are there higher rates of mutation? why?

Answer 3

organisms with short lifecycles = higher frequency of meiosis (therefore higher rate of mutation)

Question 4

define mutagen

Answer 4

chemicals or radiation which increases rate of mutation

Question 5

name 2 examples of things which can be mutagens

Answer 5

• ionising radiation (gamma, UV, X-rays)
• chemical (polycyclic hydrocarbons)

Question 6

what is a mutagen that can cause cancer called?

Answer 6

carcinogen

Question 7

define cancer

Answer 7

uncontrolled division of cells and the production of a tumour

Question 8

explain how mutations in tumour suppressor genes cause cancer

Answer 8

gene mutate so there’s a lack of proteins, which halts cell division or lack of receptors for these proteins

Question 9

explain how mutations in proto-oncogenes cause cancer

Answer 9

mutate producing an oncogene which releases an excess of proteins to stimulate cell division or excess receptors for these proteins

Question 10

what is a mutated proto-oncogene called?

Answer 10

oncogene

Question 11

deletion and insertion mutations cause a ….. mutation

Answer 11

frameshift

Question 12

if a substitution changes the amino acid, what specific type of mutation is it?

Answer 12

missense mutation

Question 13

if a substitution does not change the amino acid, what specific type of mutation is it?

Answer 13

silent mutation

Question 14

if a substitution changes the amino acid to a “stop”, what specific type of mutation is it?

Answer 14

nonsense mutation

Question 15

name the organelles involved in production of a glycoprotein found on the outer surface of the cell

Answer 15

nucleus, ribosomes, RER, golgi body, secretory vesicles, mitochondria

Question 16

what is the highest level of protein structure shown in haemoglobin?

Answer 16

quaternary, 4 polypeptide chains

Question 17

what is it called when there are 3 copies of chromosome 21?

Answer 17

Trisomy 21 (Downs syndrome)

Question 18

what’s the name of this phenotype (trisomy 21)?

Answer 18

Downs syndrome

Question 19

give the sex chromosomes for male and female

Answer 19

male: XY
female: XX

Question 20

suggest how meiosis could lead to Trisomy 21

Answer 20

non sister chromatids fail to separate = abnormal number of chromosomes

Question 21

what is Polyploidy?

Answer 21

having 3+ complete sets of chromosomes (e.g. 3n or 4n)

Question 22

give an example of Polyploidy

Answer 22

banana’s (triploid)

Question 23

why are triploid plants generally infertile?

Answer 23

uneven number of chromosome sets (3n), prevents homologous pairs forming correctly during prophase of meiosis I)