Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

AL. AQA Biology > genetics > Flashcards

genetics Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

why are males more likely to suffer from recessive diseases?

A

beacuase all genes on the non-homologous section of the chromosome have no corresponding chromatid on the Y chromosome, therefore will be expressed in the phenotype

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

autosomes

A

other chromosomes in the body (not sex chromosomes) - 22 pairs we inherit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

codominance

A

when alleles of a gene have equal dominance - meaning that individual will have a different phenotype to either of the homozygous individuals, as both alleles expressed in phenotype

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

gene pool

A

all the alleles of a gene within a population of a species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

allele frequency

A

number of organisms in a community which carry a particular allele

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

hardy-weinberg equation

A

1 = p2 + 2pq + q2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what does hardy-weinberg equation predict

A

frequency of dominant and recessive alleles in a population as long as certain factors remain the same

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

assumptions made about hardy-weinberg equation (5)

A
  • no mutations arise
  • population is isolated - no allele flow in or out of pop.
  • no selection - all alleles equally as likely to be passed on
  • population is large
  • mating is random
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

gene

A

a short section of DNA which determines a particular characteristic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

variation

A

minor differences between individuals of the same species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

monohybrid inheritance

A

inheritance of a single characteristic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

locus

A

position of a gene on a chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

multiple alleles

A

some genes may have multiple alleles to code for 1 phenotype (eg. blood groups) but a gene will only EVER consist of 2 alleles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

heterosomes

A

sex chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

why are recessive alleles on non-homologous part of X chromosome always shown in the phenotype of a male?

A
  • because no corresponding chromatid on Y

- means mutated recessive alleles will be seen resulting in sex-linked disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

dihybrid inheritance

A

inheritance of 2 pairs of charecteristics (eg. tall plants an purple flowers)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what phenotype ratios will you usually get with dihybrid inheritance (homozygous individuals - eg. TT, tt, RR, rr)

A

9:3:3:1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

co-dominant genes

A

both alleles in a gene are equally expressed (eg. black + white = grey offspring) – alleles are both equally as dominant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

when will you see 9:3:3:1 dihybrid inheritance

A

when NO crossing over in Meiosis occurs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

epistasis

  • occurs?
A

expression of one gene hides the expression of another

  • metabolic proceses controlled by enzymes coded for by different genes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

principle that hard Weinberg is based on

A

frequency of dominant and recessive alleles in a population will remain the same from generation to generation provided certain conditions remain the same

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

transcription factors

A

specific molecules which move fro, cytoplasm, into nucleus to switch on/off genes so that transcription ca occur/be prevented

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

how do transcription factors work?

A
  • transcription factor has site which is complimentary to specific base sequence on DNA
  • when it binds to PROMOTER REGION It causes transcription of the base to begin
  • mRNA produced and information it carries is translated into a polypeptide
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

how does oestrogen activate transcription factor?

A
  • lipid soluble so diffuses into cytoplasm, through phospholipid bilayer membrane
  • binds to receptor site on transcription factors as it has a complimentary shape
  • changing the shape of the DNA binding site on the transcription factor so it can now bind to base sequence on DNA
  • transcription factor enters nucleus through nuclear pore - binds to specific PROMOTER REGION of DNA
  • combination of transcription factor with DNA stimulates transcription of gene which makes up that portion of DNA - gene switched on
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

phenotype

A

physical characteristics due to genotype and environmental factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Recessive epistasis

A

Recessive epistasis is where the epistatic allele (the allele that masks another gene) is recessive therefore 2 copied must be present to effect expression of another gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

phenotypic ratio

A

ratio of different phenotypes in offspring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

linked genes

- why?

A

ones on same autosome - because they’ll stay together during independent segregation of chromosomes in meiosis 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

the closer 2 linked genes are…

why?

A

the more closely they are linked

because they are less likely to be split up by crossing over

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

if 2 genes are autosomally linked you won’t..

A

get expected phenotypic ratio you expect in offspring of a cross

31
Q

what does a 12:3:4 ratio suggest?

A

dominant epistasis

32
Q

stages of gene cloning using plasmids

A
  • gene of intrest is isolated

-

33
Q

what is p and q in HW?

A

allelic frequency

34
Q

what is p2 and q2 in HW?

A

phenotypic frequency

35
Q

genetic causes of variation (4)

A
  • mutation
  • crossing over of chromatids in meiosis 1 means each of 4 daughter cells formed have chromatids with different alleles
  • independent segregation of chromosomes
  • random fertilisation of gametes in sexual reproduction
36
Q

how does independent segregation cause variation

A
  • each homologous pair of chromosomes is made up of 1 maternal + 1 paternal - when separated in meiosis 1 its random which chromosome from which pair ends up In daughter cells as line up randomly along equator of cell ∴ different combinations of maternal and paternal chromosomes = variation in offspring
37
Q

factors causing variation

A

genetic AND environmental

38
Q

features of genetically varied group of organisms:

A

organisms fit into a few discrete categories with no intermediate types )eg. Blood groups) - often controlled by a single gene

39
Q

types of environmental factors influencing variation (3)

A
  • climatic conditions (temp, rainfall, sunlight)
  • soil conditions (pH)
  • food availability
40
Q

features of an environmentally varied group of organisms:

A

often a continuum of characteristics - can plot a distribution curve
- variation is controlled by many genes - polygenes

41
Q

law of independent assortment

A

each member of a pair of alleles may combine randomly with each other/another pair

42
Q

autosomal linkage

A

2+ genes on same autosome are linked

43
Q

linkage group

A

all genes on a chromosome

44
Q

epistasis

A

when expression of allele of one gene masks or affects expression of another in the phenotype

45
Q

problems with injecting insulin into another person

A
  • cost
  • immune response
  • risk of infection
46
Q

recombinant DNA

A

DNA from 2 different organisms combined

47
Q

overall process of making recombinant DNA

A
  • genes isolated
  • genes cloned
  • transferred to microorganism
  • microorganism grows and acts as a factory for continual production of desired protein
48
Q

transgenic

A

organism containing recombinant DNA

49
Q

why does recombinant DNA work in producing transgenic organisms

A

because genetic code is universal - mechanisms of transcription and translation are the same

50
Q

3 methods of producing DNA fragments

A

1 - conversion of RNA to cDNA by REVERSE TRANSCRIPTASE
2 - using RESTRICTION ENDONUCLEASES to cut fragments containing desired gene from DNA
3 - creating gene in GENE MACHINE

51
Q

how does reverse transcriptase work in producing DNA fragments

A
  • cell which rapidly produces protein is selected (as have a large amount of relevant DNA ∴ easily extracted
  • reverse transcriptase used to make cDA from mRNA
  • DNA polymerase used to join complimentary nucleotides on cDNA template to make double strand w required gene
52
Q

how does restriction endonucleases work in producing DNA fragments

A
  • cute double strand at specific base sequence (many types each cutting at different base sequences = recognition sites)
  • if cut in staggered fashion they leave unpaired, exposed bases on each end of DNA strand
53
Q

how does gene machine work in producing DNA fragments

A
  • amino acid sequence used to work out DNA triplet found from desired protein
  • desired nucleotide base sequence fed into computer
  • sequence checked to make sure it meets safety standards
  • computer designs series of overlapping nucleotides - assemble into desired gene
  • gene replicated in PCR (complimentary strand assembled and multiplied to give many copied)
  • inserted into vector using sticky ends
54
Q

advantages of gene machine in production of DNA fragments (3)

A
  • DNA produced is free of nucleotides
  • great accuracy
  • any nucleotide sequence can be produced
55
Q

what does in vivo cloning produce?

A

bacteria with recombinant DNA which PRODUCE desired protein

56
Q

what does in vitro cloning involve

A

PCR

57
Q

PCR

A

polymerase chain reaction

58
Q

process of in vivo cloning

A
  • same restriction endonuclease used to cut DNA fragments (via hydrolysis reactions) and plasmid so that sticky ends are complimentary
  • joined using DNA ligase
  • promoter region needed for binding of transcription factors ( and terminator region )
  • plasmid added to bacteria with DNA ligase, restriction endonuclease and primers - mixed in medium containing calcium ions at correct temp making membrane permeable
59
Q

why may not all bacteria take up plasmid with desired gene

A
  • only a few bacteria take up plasmid
  • some plasmids close up again before gene is inserted
  • some sticky ends on the gene fragments join together to make plasmids
60
Q

how to identify genes which have taken up plasmid WITH gene?

A

replica plating

61
Q

PCR process

A
  • seperation of 2 DNA strands by breaking H bonds - 95C
  • addition of primers at 55C - primers join to ends by complimentary base pairing giving starting sequence for DNA polymerase
  • synthesis of DNA - temp raised to 72C - optimum temp for DNA polymerase making phosphodiester bonds via condensation reactions
62
Q

number of gene fragments in PCR increases…

A

exponentially

63
Q

cell differentiation

A

process by which cells develop into specialised cell suited for its role

64
Q

stem cells

A

cells which can differentiate into other types of cell

65
Q

sources of stem cells (4)

A
  • embryonic stem cells
  • umbilical cord stem cells
  • placental stem cells
  • adult (eg. bone marrow)
66
Q

totipotent stem cells

  • what?
  • where?
A
  • differentiate into ANY cell

- in zygote

67
Q

pluripotent stem cells

  • what?
  • where?
A
  • differentiate into ALMOST any cell type

- embroyos

68
Q

multipotent stem cells

  • what?
  • where?
A
  • differentiate into LIMITED NUMBER of of specialised cells

- in adults

69
Q

unipotent stem cells

  • what?
  • where?
A
  • differentiate into SINGLE TYPE of cell

- tissues/organs

70
Q

Induced pluripotent cell (iPS)

A

type of pluripotent cell which is produced in lab by genetic alteration of any unipotent body cell to make it acquire characteristics of embryonic stem cells

71
Q

what does iPS cell formation involve?

A

transcription factors and genes

72
Q

uses of iPS cells (5)

A 
- regrow damaged tissues - eg skin grafts 
treating:
- leukaemia 
- parkinsons
- multiple sclerosis 
- type 1 diabetes
73
Q

main genetic sources of variation

A
  • metaphase 1 - random assortment of HOMOLOGOUS CHROMOSOMES + crossing over of alleles

AL. AQA Biology (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions