17. Inheritance

Question 1

what is inheritance

Answer 1

transmitting genetic information from one generation to the next

Question 2

what is a chromosome

Answer 2

tightly packaged DNA around histone proteins in a thread-like structure that carries information in the form of genes

Question 3

what is a gene

Answer 3

a section of DNA that codes for a specific protein

Question 4

what is an allele

Answer 4

different versions of the same gene

Question 5

how is sex determined by genes

Answer 5

one of the 23 pairs of chromosomes determines sex

the pair can either be XX for female or XY for a male

Question 6

describe how genes determine the order of amino acids in a protein

Answer 6

the sequence of bases in a gene relates directly to the amino acids added during protein synthesis

Question 7

how does DNA control cell function

Answer 7

DNA code for protein which can be enzymes, antibodies and receptors

Question 8

explain protein synthesis

Answer 8

• a copy of the gene is made using mRNA and taken into the cytoplasm to a ribosome
• the ribosome assembles amino acids into protein based on the sequence of bases in the mRNA molecule

Question 9

compare the genes found in all the body cells

Answer 9

• all body cells contain the same genes
• however genes can be turned on or off dependent on the proteins the cell needs to make

Question 10

what is a haploid nucleus

Answer 10

a nucleus with one set of unpaired chromosomes

Question 11

what is a diploid nucleus

Answer 11

a nucleus with two sets of chromosomes where there is a pair of each type of chromosome

Question 12

how may pairs of chromosomes does a human diploid cell have

Answer 12

23 pairs

Question 13

what is mitosis

Answer 13

a type of nuclear division that produces two genetically identical daughter cells

Question 14

state 4 uses of mitosis

Answer 14

• growth
• replacing worn out cells
• repairing tissues
• asexual reproduction

Question 15

when does the duplication of chromosomes happen in relation to mitosis

Answer 15

the duplication of the chromosomes happens before mitosis

Question 16

how is chromosome number maintained during mitosis

Answer 16

• the chromosome number doubles prior to mitosis
• during mitosis, each of the copies are separated, giving each daughter cell the original amount (23 pairs)

Question 17

what are stem cells

Answer 17

cell that do not lose the ability to differentiate and so can differentiate into many different types of cells

Question 18

what is meiosis

Answer 18

a type of nuclear division that produces four daughter cells that are not genetically identical

Question 19

what type of cell does meiosis produce

Answer 19

sex cells/gametes

Question 20

how does meiosis produce genetically different daughter cells

Answer 20

meiosis combines maternal and paternal chromosomes in different ways

Question 21

what is the genotype

Answer 21

the genes present for a trait

Question 22

what is the phenotype

Answer 22

the visible characteristic

Question 23

what is meant when an organism is homozygous

Answer 23

when an organism has two copies of the same allele

Question 24

what is meant when an organism is heterozygous

Answer 24

when an organism has two different versions of the same gene

Question 25

what is the term used to describe the type of breeding carried out when two homozygous individual breed

Answer 25

pure - breeding

Question 26

what is a dominant allele

Answer 26

a version of a gene where only one copy is needed for it to be expressed

Question 27

what is a recessive allele

Answer 27

a version of a gene where two copies are needed for it to be expressed

Question 28

what do family pedigrees show

Answer 28

the inheritance of an allele over generations

Question 29

draw a Punnett square for a cross between a homozygous recessive blue eyed female (bb) with a heterozygous brown eyed male (Bb)

Answer 29

Question 30

draw a Punnett square for a cross between homozygous dominant red flower (RR) with a homozygous recessive white flower (rr)

Answer 30

Question 31

Draw a Punnett square for a cross between two heterozygous cystic fibrosis carriers (Ff)

Answer 31

Question 32

what is a test cross

Answer 32

- a method used to identify an unknown genotype - it is done by breeding the unknown organism with a homozygous recessive organism

Question 33

what is codominance

Answer 33

when two alleles affect the phenotype

Question 34

what is a sex linked characteristic

Answer 34

- a characteristic where the gene responsible for its located on a sex chromosome - this makes it more common in one sex than another

Question 35

give one example of a sex linked characteristic

Answer 35

colour blindness

Question 36

Draw a Punnett square for a cross between a female with blood type A and a male with blood type AB

Answer 36