3.1 + 3.2 genes and chromosomes

Question 1

what is a gene?

Answer 1

a heritable factor that consists of a length of DNA and influences a specific characteristic

Question 2

what are alleles?

Answer 2

the various specific forms of genes

Question 3

how are new alleles formed?

Answer 3

by mutation

Question 4

new alleles form as a result of mutations, contributing to increased…

Answer 4

genetic variation

Question 5

sickle cell anaemia is caused by ___________ mutation

Answer 5

base substituition

Question 6

why is haemoglobin different in an individual with sickle cell anaemia?

Answer 6

• due to base substitution mutation in gene coding for haemoglobin protein
• which leads to a change in the base sequence of mRNA transcribed
• this leads to a change in the sequence of polypeptide in haemoglobin

Question 7

sickle cell anaemia is an [autosomal/sex-linked] disorder

Answer 7

autosomal

Question 8

what is the difference in RBC in a healthy individual and an individual w sickle cell anaemia?

Answer 8

healthy: biconcave shape
sickle cell anaemia: sickle shaped

Question 9

what are the implications of individuals w sickle cell anaemia?

Answer 9

sickle cells may clump together and clog blood vessels, interfering w blood circulation

Question 10

sickle cell anaemia is [recessive/dominant]

Answer 10

recessive

Question 11

what are 2 symptoms of sickle cell anaemia?

Answer 11

chronic anaemia and jaundice

Question 12

what is a genome?

Answer 12

it refers to all the DNA present in an individual

Question 13

what is the human genome project for?

Answer 13

• to work out the base sequences of the human genome
• and identify the location of these genes

Question 14

what are some outcomes of the human genome project?

Answer 14

• mutations can be located and genes associated with diseases can be identified
• tests for genetic diseases can be developed → earlier detection
• evolutionary history can be studied

Question 15

prokaryotes have circular DNA while eukaryotes have _______ DNA

Answer 15

linear

Question 16

what is the opposite of naked DNA?

Answer 16

DNA associated w histones

Question 17

___karyotes have homologous chromosomes

Answer 17

eukaryotes

Question 18

eukaryotes have… but prokaryotes don’t have these

Answer 18

centromeres, telomeres, homologous chromosomes

Question 19

what enables transcription and translation to occur simulataneously in prokaryotes?

Answer 19

DNA is not membrane bound

Question 20

plasmids confer ________ traits

Answer 20

advantageous

Question 21

what are nucleosomes made out of?

Answer 21

DNA wrapped twice around octamers (8 of them) of histones

Question 22

what method was involved in Cairn’s technique?

Answer 22

autoradiography

Question 23

what is Cairn’s technique used for?

Answer 23

to measure the length of DNA molecules

Question 24

what organism did Cairn use?

Answer 24

E coli

Question 25

what did Cairn label as radioactive? and why?

Answer 25

- thymine using isotope of hydrogen - radioactive thymine would be incorporated into new DNA strands - radiation released by labelled thymine can be seen using autoradiography

Question 26

how was the DNA released from the bacteria?

Answer 26

the bacteria was lysed using enzymes, releasing DNA

Question 27

how is radioactivity seen on photographic film?

Answer 27

radioactivity darkens the film

Question 28

how does newly synthesised DNA look like on the film?

Answer 28

line of black dots

Question 29

autoradiography involves these materials:

Answer 29

1. photographic film 2. photographic emulsion

Question 30

what did Cairn's technique show?

Answer 30

E coli DNA was much longer than the E coli cells

Question 31

how many chromosomes do _Homo_ _sapiens_ have?

Answer 31

46

Question 32

how many chromosomes do _Pan_ _troglodytes_ have?

Answer 32

48

Question 33

which organism has 48 chromosomes?

Answer 33

_Pan_ _troglodytes_

Question 34

how many chromosomes does _Canis_ _familiaris_ have?

Answer 34

78

Question 35

how many chromosomes does _Oryza_ _sativa_ have?

Answer 35

24

Question 36

_Parascaris_ _equorum_ has ____ chromosomes

Answer 36

2

Question 37

which organism has 78 chromosomes?

Answer 37

_Canis_ _familiaris_

Question 38

_Homo_ _sapiens_ have ____ base pairs

Answer 38

3.2 bil

Question 39

how many base pairs does a _T2_ _phage_ have?

Answer 39

170k

Question 40

how many base pairs does a _Escherichia_ _coli_ have?

Answer 40

4.6 mil

Question 41

which organism has 130 mil base pairs

Answer 41

_Drosophilia_ _melongaster_

Question 42

__________ has the longest genome length

Answer 42

_Paris_ _japonica_

Question 43

_Paris_ _japonica_ has _____ base pairs

Answer 43

150 bil

Question 44

_Drosophilia_ _melongaster_ has _____ base pairs

Answer 44

130 mil

Question 45

what do karyograms show?

Answer 45

an organism's homologous chromosomes in decreasing length