17 Inheritance

Question 1

chromosomes

Answer 1

made of DNA: which contains genetic information in the form of genes

Question 2

gene

Answer 2

a length of DNA that codes for a protein

Question 3

Allele

Answer 3

alternate form of gene

Question 4

describe the inheritance of sex in humans

Answer 4

out of 23 pairs of chromosomes, 1 pair determines the sex of the individual. Males have XY and females have XX.

Question 5

what determines the sequences of amino acids used to make a specific protein

Answer 5

the sequences of bases in a gene

Question 6

Explain that different sequences of amino acids give different shapes to protein molecules

Question 7

How does DNA control cell function

Answer 7

By controlling the production of proteins, including enzymes, membrane carriers and receptors for neurotransmitters

Question 8

Explain how a protein is made:

Answer 8

• the gene coding for the protein remains in the nucleus
• messenger RNA (mRNA) is a copy of a gene
• mRNA molecules are made in the nucleus and move to the cytoplasm
• the mRNA passes through ribosomes
• the ribosome assembles amino acids into protein molecules
• the specific sequence of amino acids is determined by the sequence of bases in the mRNA

Question 9

Why, even though the body cells in an organism contain the same genes, not all are expressed?

Answer 9

Beacuse the cell only makes the specific proteins it needs

Question 10

haploid nucleus

Answer 10

a nucleus containing a single set of chromosomes

Question 11

diploid nucleus

Answer 11

a nucleus containing two sets of chromosomes

Question 12

What’s in a diploid cell

Answer 12

A pair of each type of chromosome and in a human diploid cell there are 23 pairs

Question 13

mitosis

Answer 13

nuclear division giving rise to genetically identical cells

Question 14

role of mitosis

Answer 14

growth, repair of damaged tissues, replacement of cells and asexual reproduction

Question 15

what occurs before mitosis

Answer 15

the exact replication of chromosomes

Question 16

what occurs during mitosis

Answer 16

the copies of chromosomes seperate, maintaining the chromosome number in each daughter cell

Question 17

stem cells

Answer 17

unspecialised cells that divide by mitosis to produce daughter cells that can become specialised for specific functions

Question 18

meiosis

Answer 18

a reduction division in which the chromosome number is halved from diploid to haploid ruslting in genetically different cells

Question 19

what process is involved in the production of gametes

Answer 19

meiosis

Question 20

inheritance

Answer 20

the transmission of genetic information from generation to generation

Question 21

describe genotype

Answer 21

the genetic make up of an organism (and in terms of the alleles present)

Question 22

describe phenotype

Answer 22

the observable features of an organism

Question 23

describe homozygous

Answer 23

two identical alleles of a particular gene

Question 24

pure breeding

Answer 24

when two identical homozygous individuals breed together

Question 25

describe heterozygous

Answer 25

having two different alleles of a particular gene

Question 26

what type of inidividual will not be purebreeding?

Answer 26

a heterozygous individual

Question 27

dominant allele

Answer 27

an allele that is expressed if it is present in the genotype

Question 28

recessive allele

Answer 28

an allele that is only expressed when there is no dominant allele of the gene present in the genotype

Question 29

3 Explain how to use a test cross to identify an
unknown genotype

Answer 29

by crossing two parents to see the phenoypic ratio of the offspring produced.
- a homozygous recessive individual should be crossed with the unknown genotype individual

Question 30

Codominance

Answer 30

a situation in which both alleles in heterzygous organisms contribute to the phenotype

Question 31

Which blood types are dominant and which are recessive?

Answer 31

A and B are dominant. O is recessive.

Question 32

sex-linked characteristic

Answer 32

a feature in which the gene responsible is located on a sex chromosome and that this makes the characteristic more common in one sex than in the other

Question 33

example of sex linkage

Answer 33

red-green colour blindness