Brainscape's Knowledge GenomeTM

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


See full index

BIOSCI 101 > Section 3: Genetics > Flashcards

Section 3: Genetics Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards Psychology 101 flashcards Chemistry 101 flashcards Biology 101 flashcards Organic Chemistry 101 flashcards Sociology 101 flashcards
1
Q

Gene

A

A discrete unit of heredity

Consists of a specific DNA or RNA sequence

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

Allele

A

Alternative versions of a gene

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

Homozygous

A

An organism having a pair of identical alleles for a trait, e.g. pp

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

Heterozygous

A

An organism having two diff alleles for a trait, e.g. Pp

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

Genotype

A

An organism’s genetic makeup

e.g. PP, Pp, pp

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

Phenotype

A

An organism’s expressed traits

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

When replicated, a chromosome has __ sister chromatids

A

2

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

Karyotype

A

The visual representation of a species chromosomes arranged in pairs at mitotic metaphase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Karyotype - replicated chromosomes

A

View replicated chromosomes because this is where we see chromosomes easily - when they’re condensed and replicated = easiest to characterise

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

Reproduction

A

When an entity undergoes division and results in the production of 2 entities of the same kind
Based on reproduction of cells and the cells’ genetic material

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

Reproduction - unicellular vs multicellular organisms

A

Unicellular - produces an entire individual

Multicellular - allows growth and repair

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

Mitotic cell division results in…

A

Production of 2 genetically identically daughter cells

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

Asexual reproduction

A

One parent
Single parent contributes all the genes
Clones (copies)
Mitosis

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

Sexual reproduction

A

2 parents
Each parent contributes half their genes
Vary genetically

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

How often are somatic cells reproducing

A

Continuously

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

Mitosis and cell cycle

A

Interphase (~90%):
G1
S phase (DNA synthesis)
G2

Mitotic (M) phase:
Mitosis
Cytokinesis

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

Amount of DNA cells during cell division

A

S phase: amount of DNA doubles because each chromosome replicates itself
G2: amount is maintained
M phase: reduces back down to half - production of 2 genetically identical cells

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

Non-replicated chromosomes

A

Consist of one piece of double-stranded DNA

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

Mitosis: S phase

A

Duplication of chromosome

Consists of 2 sister chromatids which are genetically identical

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

Mitosis: Interphase (G2)

A

Chromosomes already replicated

Chromosomes in form of chromatin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Chromatin

A

Uncondensed chromosomes

Chromosomes spend most of their lifecycle in this uncondensed phase

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

Chromatin

A

Uncondensed chromosomes

Chromosomes spend most of their lifecycle in this uncondensed phase

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

Mitosis: Prophase

A

Chromosomes start to condense into sister chromatids
Centromeres visible
Asters start to move to either pole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Why do chromosomes condense into chromatids

A

So it’s easier for them to divide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Chromosomes: Centromeres

A

Primary constriction in chromosome

Where spindles attach

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

Mitosis: Prometaphase

A

Spindles have attached to the kinetochores at the centromeres
Nuclear membrane breaking down
Chromosomes start to line up on metaphase plate

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

Mitosis: Metaphase plate

A

An imaginary line drawn through the cell

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

Mitosis: Metaphase

A

Replicated chromosomes line up along metaphase plate with each sister chromatid pointing to each pole
As they get pulled apart by spindles, each sister chromatid goes to each pole

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

Mitosis: Anaphase

A

Sister chromatids continue moving towards each pole and cells start to divide (including the cellular components)

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

Mitosis: Telophase and cytokinesis

A

Cleave furrow
Nucleolus forming
Nuclear envelop forming

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Mitosis - stages

A 
(Interphase)
Prophase
Prometaphase
Metaphase
Anaphase
Telophase and cytokinesis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Life cycle

A

Sequence of stages in an organism’s reproductive history

Conception to production of a new offspring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Fertilisation

A

The fusion of 2 haploid gamete nuclei to form diploid zygote nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Haploid

A

A single set of chromosomes (n)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Diploid

A

The condition in which each autosome is represented twice (2n)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Meiosis

A

2 successive nuclear division in which a single diploid cell forms 4 haploid nuclei

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Humans

A

Multicellular diploid organisms

2n = 46, i.e. 23 pairs of chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Humans - reproductive cells

A

Sperm and eggs
Contain half the genetic material the rest of our body does
Egg + sperm –> zygote (restores 2n) –> develops into individual

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Meiosis - stages

A 
(Interphase)
Prophase I
Metaphase I
Anaphase I
Telophase I and cytokinesis

Prophase II
Metaphase II
Anaphase II
Telophase II and cytokinesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Meiosis: Interphase

A

Chromatin

Already replicated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Meiosis: Prophase I

A

Condensed down into chromosomes

When 2 homologous pairs that are replicated come tgt, non-sister chromatids can cross over, i.e. exchange DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Does crossing over occur in mitosis

A

Yes, but not exactly the same because cells are identical

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Meiosis: Metaphase I

A

Chromosomes line up in their homologous pairs

Orientated randomly on metaphase plate - important for generating variation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Meiosis: Anaphase I

A

Replicated chromosomes move to either side of pole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Meiosis II

A

Individual chromosomes line up along metaphase plate and each of the sister chromatids goes to either pole
Results in 4 haploid gametes containing half the genetic material we started with

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Meiosis: Independent assortment - which stage does this occur

A

Metaphase I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Meiosis: Independent assortment

A

Homologous pairs align in a random orientation on metaphase plate
Each maternal and paternal homologue assorts independently of other pairs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Meiosis: Crossing over - which stage does this occur

A

Prophase I

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Meiosis: Crossing over

A

The exchange of genetic material between non-sister chromatids
Produces recombinant chromosomes, i.e. chromosomes carrying genes derived from each parent
Shuffles the genes within the chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Meiosis: Crossing over in humans

A

1-3 crossover events occur per chromosome pair

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Meiosis: What processes add to genetic variation

A

Independent assortment
Crossing over
Random fertilisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Meiosis: Why is crossing over essential

A

Essential for cell division otherwise don’t line up and divide properly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Meiosis I vs II

A

I: homologous pairs lined tgt, and one of the pairs goes to one pole and other goes to other pole
II: separated chromosomes line up and get separation of sister chromatids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Mendelian laws: First law

A

Principle of segregation
The 2 alleles segregate during gamete production
The diploid state is restored by fusion of gametes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Mendelian laws: Second law

A

Principle of independent assortment
When on diff chromosomes, each allele pair assorts independently of other allele pairs during gamete formation
i.e. one gene behaves independently of other gene, but ONLY if those 2 genes are located on diff chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

Chromosome theory of inheritance - parallel

A

Parallel behaviour of Mendel’s genes and behaviour of meiotic chromosomes

  • pairing
  • segregation
  • independent assortment
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

Cystic fibrosis

A

NZ’s most common lethal genetic disease

Normal/unaffected allele is dominant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

Incomplete / partial dominance

A

Dominant allele is not fully expressed in heterozygote
Heterozygote has an intermediate phenotype because only having one copy allows you to convert only half the precursor
e.g. cross red + white = pink

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

Co-dominance

A

Full expression of both alleles in the heterozygote

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

Co-dominance: ABO blood group

A

Diff alleles responsible for expressing a carbohydrate on surface of RBCs
A expresses A carbohydrate
B expresses B carbohydrate
O expresses none

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

Co-dominance: ABO blood group - antibodies

A

AB: bursts with A and B
AA and AO: bursts with A
BB and BO: bursts with B
OO: doesn’t burst

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

Co-dominance: ABO blood group - carbohydrate and alleles

A

Carb A: I(A)
Carb B: I(B)
No carb: i

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

The gene encoding for the ABO blood group is an example of a gene with _____

A

Multiple alleles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

Co-dominance: ABO blood group - phenotype and genotype

A

A: I(A)I(A) or I(A)i
B: I(B)I(B) or I(B)i
AB: I(A)I(B)
O: ii

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

Multiple alleles

A

Every individual has 2 alleles, but in the population there can be more alleles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

DNA fingerprinting

A

Each individual has 2 alleles (of diff sizes), but there are many alleles in the pop (~3000)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

No of genes per genome vs no of chromosomes

A

No of genes per genome far exceeds the no of chromosomes

Therefore must be more than one gene per chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

How many genes does each chromosome contain

A

Hundreds or thousands

except Y chromosome which has ~16 genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

Are most of our genes inherited in the Mendelian fashion

A

No because they’re all located on the same chromosome –> tend to be inherited tgt

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

Linked genes

A

Genes that are located on the same chromosomes and tend to be inherited tgt
Exceptions to Mendelian inheritance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

Test cross

A

Crossing a heterozygous and homozygous recessive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

Test cross: +

A

+ is dominant form

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

Results of a testcross - possible progeny

A 
Aa Bb (non-recombinant)
aa bb (non-recombinant)
Aa bb (recombinant)
aa Bb (recombinant)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

Results of a testcross: Independent assortment

A

Aa Bb 25%
aa bb 25%
Aa bb 25%
aa Bb 25%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

Results of a testcross: Complete linkage

A

Aa Bb 50%

aa bb 50%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

Results of a testcross: Linkage with some crossing over

A

Aa Bb and aa bb = more than 50%

Aa bb aa Bb = less than 50%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

Recombination frequency =

A

(No of recombinants /

total no of offspring) x 100 = %

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

Mapping a chromosome using recombinant frequencies assumes…

A

That crossing over occurs randomly, then the frequency that crossing over occurs should be proportional to the distance between 2 genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

1% recombinant frequency = ?

A

1 map unit or 1 centimorgan (cM)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

What can recombinant frequencies be used for

A

Build linear chromosome maps

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

Genetic map

A

The order that loci occur along a chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

Linked genes - parental vs recombinant genes

A

Outside genes can’t combine –> parental type

Adjacent can recombine –> recombinant - the further apart they are on the chromosome, the more recombinant there is

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

Total recombination frequency for 2 genes tgt is less than the sum of the genes separately - why

A

Double crossing over can occur –> turns back into parental type –> reduces recombination frequency
Tends to result in underestimation of big genetic distances

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

Sex-linked traits: Morgan’s first mutant - experiment + results

A

P generation: Homozygous female (red eyes), male (mutant X chromosome and Y chromosome) (white eyes)

F1 generation: All offspring red eyes

F2 generation: typical Mendelian 3:1 ratio, but all white-eyed flies males

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

XY - hemizygous

A

Many genes located on the X chromosome don’t have a homologue (corresponding allele) on the Y chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

Sex-linked traits: Morgan’s first mutant - F2 white eye

A

Female is heterozygous with a mutant, male is recessive with a Y chromosome, so must be a mutant with Y –> male

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

Heterogametic sex

A

The sex that produces two kinds of gametes and determines sex of offspring
In humans = male

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

Homogametic sex

A

The sex that produces one kind of gamete

In humans = female

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
89
Q

Chromosomes and sexual phenotype: XO

A

Missing an X chromosome
Human: sterile female
Drosophilia: sterile male

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
90
Q

Chromosomes and sexual phenotype: XX

A

Human: normal female
Drosophilia: normal female

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
91
Q

Chromosomes and sexual phenotype: XXX

A

Human: Fertile female
Drosophilia: Sterile female

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
92
Q

Chromosomes and sexual phenotype: XY

A

Human: Normal male
Drosophilia: Normal male

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
93
Q

Chromosomes and sexual phenotype: XXY

A

Human: Sterile male
Drosophilia: Fertile female

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
94
Q

Chromosomes and sexual phenotype: XYY

A

Human: Fertile male
Drosophilia: Fertile male

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
95
Q

Chromosomes and sexual phenotype: Turner’s syndrome

A

XO - sterile female

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
96
Q

Chromosomes and sexual phenotype: Klinefelter’s syndrome

A

XXY - sterile male

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
97
Q

SRY - functions

A

Determines sex
Triggers testicular development
A transcription factor (DNA binding protein)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
98
Q

Chromosome - pseudoautosomal region

A

At either end of chromosome is a pseudoautosomal region - can pair up to each other and undergo crossing over

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
99
Q

SRY - pseudoautosomal boundary

A

SRY located v close to pseudoautosomal boundary, so in some cases crossing over occurs and transfers Y gene –> males

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
100
Q

Do males / females contain female / male genes

A

Yes; males are always repressing female genes and females always repressing male genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
101
Q

Androgen receptor gene - mutation

A

Results in partial or complete inability of cells to respond to androgens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
102
Q

Androgen insensitivity syndrome (AIS)

A

Even though individual has testes and are producing androgen, their body doesn’t recognise it –> develop back into females
Extreme conditions: born female, but at 12 or 13 y/o, half of them turn into males

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
103
Q

X chromosome inactivation

A

In females, each embryonic cell randomly inactivates one of the two X chromosomes
Some genes can escape from inactivation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
104
Q

Barr body

A

Inactivated X chromosome

Densely stained objects in nuclei of females

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
105
Q

Barr body genes

A

Most Barr body genes aren’t expressed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
106
Q

Barr bodies - stability

A

Stable through mitosis, but the X is reactivated in cells that give rise to ova

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
107
Q

Males vs females - sets of genes

A

Females have 2 sets, males have 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
108
Q

X inactivation - tortoiseshell cat

A

Females consist of a mosaic of 2 types of cells; those with active X derived from father and active X derived from mother
Get a random expression of black and orange fur across the body in females only

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
109
Q

Are all genes located on nuclear chromosomes

A

No - some are located in organelles, e.g. mitochondria and chloroplasts contain small circular DNA molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
110
Q

Mitochondria genes - inheritance

A

Mostly maternal inheritance

Don’t show Mendelian inheritance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
111
Q

Mitochondria genes - function

A

Most are involved in ETC and ATP synthase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
112
Q

Mitochondrial diseases

A

Nervous system and muscles are most susceptible to energy deprivation, so are most affected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
113
Q

Organelle genes resemble…

A

A bacterial genome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
114
Q

Mitochondrial myopathy

A

Causes weakness, intolerance of exercise and muscle deterioration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
115
Q

Types of meiotic nondisjunction

A

Nondisjunction of homologous chromosomes in meiosis I

Nondisjunction of sister chromatids in meiosis II

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
116
Q

Meiotic junction - common?

A

Quite common

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
117
Q

Meiotic nondisjunction: Meiosis I

A

Both homologous pairs go to same pole

Daughter cells: 2 of them has one extra chromosome, other 2 have 1 less chormosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
118
Q

Meiotic nondisjunction: Meiosis II

A

Separation of sister chromatids doesn’t occur

Daughter cells: 1 has one extra chromosome, 1 has one less chromosome, 2 are normal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
119
Q

Aneuploidy

A

Abnormal number of certain chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
120
Q

Trisomic

A

1 extra chromosome (3 copies)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
121
Q

Monosomic

A

1 less chromosome (1 copy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
122
Q

Nullisomic

A

Lack both chromosomes (0 copies)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
123
Q

Polyploidy

A

More than 2 complete chromosome sets

e.g. triploid (3n), tetraploid (4n)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
124
Q

Alterations to chromosome structure - severity

A

Animals cope much better with alterations to chromosome structure than with extra sets of chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
125
Q

Alterations to chromosome structure: Deletion

A

Removes a chromosomal segment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
126
Q

Alterations to chromosome structure: Duplication

A

Repeats a segment

Our genome is full of this

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
127
Q

Alterations to chromosome structure: Inversion

A

Reverses a segment

Results in decreased gamete viability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
128
Q

Alterations to chromosome structure: Translocation

A

Moves a segment from one chromosome to another, non-homologous one

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
129
Q

Alterations to chromosome structure: Reciprocal translocation

A

Most common type

Non-homologous chromosomes exchange fragments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
130
Q

Alterations to chromosome structure: Non-reciprocal translocation

A

A chromosome transfers a fragment without receiving a fragment in return

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
131
Q

Alterations to chromosome structure: Gene families are formed from…

A

Duplication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
132
Q

Human disorders due to chromosomal alterations: Down’s syndrome

A

Karyotype shows trisomy 21, the most common cause

Correlates with maternal age

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
133
Q

Smallest chromosome

A

Chromosome 21

134
Q

Nondisjunction of sex chromosomes produces a variety of…

A

Aneuploid conditions, most of which appear to upset genetic balance less than conditions involving autosomes

135
Q

Why is genetic balance less affected in sex chromosomes than in autosomes

A

Y chromosome carries few genes

Extra copies of X chromosome are inactivated as Barr bodies

136
Q

Can males have Barr bodies

A

Yes, but few

137
Q

Klinefelter’s syndrome

A

XXY
Individuals have male sex organs, are sterile and have abnormally small testes
Extra X is inactivated, but some breast enlargement and other female characteristics are common

138
Q

Turner’s syndrome

A

XO
Phenotypically female but sterile as their sex organs don’t mature
If provided with oestrogen replacement, can develop secondary sexual characteristics

139
Q

Chronic myeloid leukemia (CML)

A

Reciprocal translocation
A result of translocation between chromosome 9 and 22
In cancer cells in nearly all patients contain a short chromosome 22 and abnormally long chromosome 9

140
Q

What is the phenotype of an individual determined by

A

Interactions between alleles at the same time, and in many cases at a no of diff loci, as well as by the environment

141
Q

Pleiotropy

A

A single gene having multiple phenotypic effects

142
Q

Pleiotropy - cystic fibrosis

A 
CFTR gene mutation
Results in defective/absent Cl- channels
Results in multiple traits affected:
- chronic bronchitis
- poor absorption of nutrients in intestine
- block pancreatic and bile ducts
143
Q

Epistasis

A

When one gene/locus affects the phenotype of another gene

e.g. recessive e genes may result in no pigment regardless of B or b gene

144
Q

Continuous phenotypic variation is…

A

A complex trait

145
Q

Continuous phenotypic variation: Human skin colour

A

Controlled by many genes
Evidence suggests at least 3 genes
Dark skin allele (A, B or C) is incompletely dominant to other alleles

146
Q

Continuous phenotypic variation: Human skin colour - alleles

A

AABBCC very dark, aabbcc very light

Alleles have additive effect, so AaBbCc and AABbcc same skin colour because both have 3 dominant alleles

147
Q

Continuous phenotypic variation: Human skin colour - what can help smooth the curve

A

Environmental factors

148
Q

Phenotypic range

A

Range of phenotypes that can be produced

149
Q

When is the phenotypic range broadest

A

Broadest for polygenic traits

150
Q

Is there a gene for everything

A

No - some traits occur above the genetic level

151
Q

Norms of reaction

A

The environmental effect on the phenotype

152
Q

Norms of reaction - ABO blood group

A

Norm of reaction has no breadth = given genotype always results in same phenotype

153
Q

What does norm of reaction allow us to do

A

Gives us a way to quantify the response of the phenotype by the environment
i.e. fix genotype and vary environment, how much does the phenotype vary?

154
Q

When are norm of reactions greatest

A

For polygenic traits

155
Q

Genetic diseases can have a big…

A

Environmental component

156
Q

Developmental noise

A

Random events in development leading to variation in phenotype
A slight difference in division in the beginning will result in a significant difference at end

157
Q

Epigenetic landscape

A

Imagines the organism is a ball sitting at top of valley
Through development, ball rolls down the landscape
Environment can push ball in diff directions
Shape of landscape is determined by genes which could pull it to diff shapes
Small changes in genes in an area could change where the ball moves
Ball seesaws up and down valley, but eventually reaches end - phenotype

158
Q

Germline mutations - effect on gene pool

A

New germline mutations immediately change the gene pool of a pop by creating a new allele

159
Q

Mutations in coding regions - commonality

A

Relatively rare

Reflects high fidelity of DNA replication

160
Q

Mutations - random?

A

Mutations are random - they occur in any gene without regard to the benefit of that cell

161
Q

Somatic vs germline mutations

A

Somatic: not transmitted to progeny
Germline: transmitted to some or all progeny

162
Q

Where in a gene do most mutations occur

A 
Certain regions (introns) are more prone to mutations because they don't affect the protein produced
Fewer exon mutations
Most exon variation doesn't change amino acid sequence (neutral)
163
Q

Area of mutation within germline can result in…

A

Either a normal or mutant progeny

164
Q

Most mutations are ____

A

Neutral - no phenotypic effect

165
Q

Genetic disorder / hereditary disease

A

When a mutation has an adverse effect on phenotype / function

166
Q

Sickle-cell disease - mutation

A

Caused by substitution of a single amino acid in haemoglobin protein of RBC
Amino acid Glu –> Val –> change in function

167
Q

Sickle-cell disease - what happens

A

When O2 content of individual’s blood is low, the sickle-cell haemoglobin protein aggregates into long fibrous chains –> deforms RBC (more rigid) –> difficult to move through BVs

168
Q

Sickle-cell disease - symptoms

A

Physical weakness
Pain
Organ damage
Paralysis (blockage of small BVs)

169
Q

Sickle-cell disease - haemoglobin protein

A

2 alpha and 2 beta genes

170
Q

Sickle-cell disease - commonality

A

Most common inherited disorder among people of African descent

171
Q

Sickle-cell disease - 1 vs 2 copies

A

Individuals with 2 copies of sickle-cell allele manifest the disease fully
Heterozygous inherit some of the symptoms - said to have the sickle-cell trait

172
Q

Population

A

A group of individuals of the same species that live in the same area and interbreed

173
Q

Gene pool

A

The sum of all alleles of all genes of all individuals in the pop

174
Q

Hardy-Weinberg equilibrium

A

Allele and genotype frequencies in a pop will remain constant from one generation to the next

175
Q

Hardy-Weinberg equation - allows calculation of…

A

The expected genotype frequencies given the observed allele frequencies

176
Q

Hardy-Weinberg is a model of ______

A

Stability

177
Q

Calculation of allele frequencies: No of alleles =

A

2 x no of individuals with that genotype

178
Q

Calculation of allele frequencies: Dominant allele frequency

A

(no of DD individuals x 2) + (no of Dd individuals)

179
Q

Calculation of allele frequencies: Recessive allele frequency

A

(no of dd individuals x 2) + (no of Dd individuals)

180
Q

Hardy-Weinberg equations

A

p^2 + 2pq + q^2 = 1
p + q = 1

p = dominant
q = recessive
p^2 = frequency of RR
pq = frequency of Rr
q^2 = frequency of rr
181
Q

Conditions for Hardy-Weinberg

A 
No mutations
Mating occurs at random
No selection
Extremely large pop size
No gene flow
182
Q

Conditions for Hardy-Weinberg: No mutations

A

The gene pool is modified if mutations changes alleles

183
Q

Conditions for Hardy-Weinberg: Mating occurs at random

A

If individuals mate with a subset of the pop, genotype frequencies change

184
Q

Conditions for Hardy-Weinberg: No selection

A

Differences in survival and reproduction of individuals with diff genotypes can alter allele frequencies

185
Q

Conditions for Hardy-Weinberg: No gene flow

A

Movement of individuals in and out of a pop can alter allele frequencies

186
Q

Non-random mating affects…

A

The way alleles combine to form genotypes and alters genotype frequency

187
Q

Outbreeding

A

Promotes variability

188
Q

Inbreeding

A

Results in loss of variation
Matings between second cousins or closer are more likely to produce homozygous genotypes for otherwise rare autosomal recessive genes

189
Q

Cystic fibrosis - A child resulting from mating between first cousins has a ____ greater risk of being affected

A

~7-fold

190
Q

Self-fertilisation removes….

A

Variation

191
Q

Genetic drift

A

The change in allele frequencies as a result of change events
Overall affect is a loss of genetic variation

192
Q

Genetic drift has major effects in _____ populations

A

Small

193
Q

Genetic drift: Founder effect

A

When a small pop branches off from a larger one

By chance, the small pop may not have all the alleles present in the larger pop

194
Q

Genetic drift: Population bottlenecks

A

Occur when a pop is drastically reduced in numbers

Chance effects can result in loss or fixation of alleles

195
Q

Genetic drift: Fixation

A

Loss of other alleles

196
Q

Gene flow

A

Movement of alleles into or out of a pop due to movement of individuals or their gametes
Tends to reduce differences

197
Q

If gene flow is greater enough…

A

It can result in 2 pops combining into a single common gene pool

198
Q

Recombinant DNA technology

A

Genes or DNA from 2 diff sources are combined in vitro in the same molecule

199
Q

In vitro

A

In the lab / test tube

200
Q

Restriction enzymes - how do they work

A

Cut DNA at specific sequences 4-8 bp in length

201
Q

Restriction enzymes - bacteria

A

Isolated from bacteria where they protect bacteria from intruding DNA, e.g. phages

202
Q

How many restriction enzymes

A

Hundreds; most of which have diff recognition sequences and cut the DNA at diff places (specific)

203
Q

Restriction sites - symmetry

A

Most are symmetrical but cleave the DNA backbone in a staggered / asymmetrical way –> single-stranded ends called sticky ends

204
Q

Recombinant DNA - what DNA is combined

A

Usually combine an organism’s DNA (e.g. human or bird) with bacteria DNA

205
Q

What is the sticky end useful for

A

Cloning DNA

206
Q

Bacterial plasmid

A

A naturally occurring small circular piece of autonomous DNA but have been genetically modified to act as a vector
Can replicate inside a host bacterial cell

207
Q

Vector

A

A piece of DNA that can carry another piece of DNA

Used to insert pieces of DNA into bacteria

208
Q

Mixing vector and foreign DNA

A

Mixing them in the appropriate conc causes them to H bond to each other

209
Q

If the insert DNA is cut with the same restriction enzyme as the cloning vector…

A

They’ll have complementary sticky ends –> can form H bonds

210
Q

DNA ligase

A

Covalently links 2 pieces of DNA tgt

Catalyses formation of covalent bonds that close sugar-phosphate backbone

211
Q

Cloning genes and DNA ligase

A

Insert DNA is cut with same restriction as vector

DNA ligase permanently joins the strands tgt (because H bonds aren’t permanent)

212
Q

Lac Z gene

A

Contains restriction site

Has a promoter which when active produces enzyme beta-galactosidase

213
Q

How can we help prevent genes rejoining to each other instead of joining to plasmids

A

By dephosphorylating the ends

But this will always occur to a certain extent

214
Q

Cloning a single gene into a plasmid - steps

A

Take recombinant molecules and bacteria and punch holes in outer membrane
Give them an electric shock –> drives plasmids into bacteria
Grow for a few generations for holes to repair
Take mixture of bacteria and put them on agar plates with ampicillin
Any bacteria that don’t have bacteria can’t grow
If DNA is present that disrupts gene –> non-functional –> white - called blue-white selection

215
Q

Genomic library

A

A collection of clones that tgt contain an organism’s entire genome

216
Q

Genomic library: Shotgun cloning

A

Instead of focusing on a single gene, cloning starts with a mixture of fragments representing the entire genome

217
Q

Bacterial artificial chromosomes (BACs)

A

Commonly used as cloning vectors
Similar mechanism to plasmids but come from diff source
Have larger inserts (100-300kb) so need less clones and can be stored as cells in a multi-well plate

218
Q

Disadvantage of plasmids

A

Can only take a relatively small chunk of DNA

~2000-3000 bp

219
Q

cDNA library

A

A collection of clones containing all gene sequences that are expressed in a particular tissue

220
Q

What are cDNA libraries made from

A

mRNA molecules

As a result, only contains genes that are being expressed at time of RNA extraction, i.e. tissue specific

221
Q

cDNA library - complexity

A

Less complex than genomic libraries

222
Q

cDNA don’t contain…

A

Promoters
UTRs
Introns

223
Q

What are cDNA libraries useful for

A

Studying genes responsible for specific functions

224
Q

% of genome codes for what

A

1% of our genome codes a protein

20% of our genome codes for a known function

225
Q

cDNA - disadvantage

A

Not all genes are expressed throughout life of an organism and not all genes are expressed in all tissues

226
Q

cDNA library - steps

A

Extract mRNA from cells
Design primer with sequence TTTT
Reverse transcriptase: once it has the 3’ end, it can make a DNA copy of the mRNA
Degrade mRNA
At other end, use primer on cap and do same thing, but use a normal polymerase instead –> double-stranded DNA –> clone back into DNA

227
Q

mRNA - distinctive features

A

One end has poly-A tail, other end has cap sequence

228
Q

cDNA library - primer

A

A short sequence of single-stranded DNA that can anneal to another single-stranded DNA or mRNA

229
Q

DNA hybridisation

A

Allows us to sort through the thousands of clones and find the gene of interest
Uses a DNA probe

230
Q

DNA hybridisation: DNA probe

A

A single-stranded labelled DNA fragment with similar sequence to a gene of interest - sticks
H bonds to the complementary sequence
Tagged with a radioactive or fluorescent label

231
Q

Polymerase chain reaction (PCR)

A

A 3-step process that produces millions of copies of a targeted region of DNA

232
Q

What is PCR based on

A

A heat stable DNA polymerase, which generates the second strand of DNA from a single-stranded template

233
Q

DNA polymerase can only extend…

A

Existing double-stranded regions, therefore requires a primer

234
Q

Reagents in a PCR reaction

A

Heat stable DNA polymerase
Deoxyribonucleotides (dNTPs)
2 primers (one for each strand)

235
Q

What does a PCR do

A

Amplifies / makes copies of specific regions in genome

These regions are between the two primers

236
Q

PCR - steps

A

Take genomic DNA and design 2 primers to either side of the region to be amplified
Heat DNA (denaturation) –> 2 strands come apart
Cool DNA (annealing) –> primers attach
Heat DNA (extension) –> makes a copy on either strand
–> 2 copies

237
Q

Gel electrophoresis

A

Separates macromolecules (DNA or protein) based on their rate of movement through gel in an electrical field - molecular sieve

238
Q

Gel electrophoresis - what does rate of movement depend on

A

Size
Electrical charge
Other physical properties

239
Q

Gel electrophoresis: DNA separation - what does it depend most on

A

Size / length of fragment

240
Q

Gel electrophoresis: What determines how big the holes are in the sieve

A

Conc of agarose

241
Q

Capillary DNA sequencing (dideoxy chain termination method)

A

Involves using one DNA strand to synthesise a nested set of complementary fragments

242
Q

Capillary DNA sequencing (dideoxy chain termination method) - random?

A

Synthesis is terminated randomly by addition of a fluorescently tagged ddNTP (dideoxy..) rather than a dNTP (deoxy…)

243
Q

Capillary DNA sequencing (dideoxy chain termination method) - fluorescent tag

A

There’s a diff fluorescent tag for each type of ddNTP (A, C, G, T)

244
Q

Capillary DNA sequencing (dideoxy chain termination method) - what happens to the resulting pop of molecules

A

They’re separated by electrophoresis with the fluorescent labels detected for each fragment

245
Q

Capillary DNA sequencing (dideoxy chain termination method) - what does the colour of the fluorescent tag on each fragment indicate

A

The type of nucleotide at the 3’ end

246
Q

Human genome project - three stages

A

Linkage mapping
Physical mapping
DNA sequencing

247
Q

Human genome project: Venter - shotgun sequencing

A

Skips the first two steps

Take a genomic library and sequence all of it

248
Q

Genomics

A

The study of genes, their interactions and relationships within a species and between species

249
Q

Human genome project - physical map

A

Takes pieces of DNA from libraries and hybridises them to locate where they fit in the genome

250
Q

Human genome project: Shotgun sequencing - steps

A

Cut DNA into overlapping fragments short enough for sequencing
Clone fragments in plasmids or vectors
Sequence each fragment
Order sequences into one overall sequence with computer software

251
Q

Human genome project: Shotgun sequencing - restriction enzymes

A

A range of them are used to cut the genome at diff places

252
Q

Human genome project: Shotgun sequencing - overlap

A

Only need ~20-30 bp overlap between fragments to be unique in a genome –> will join them tgt

253
Q

Bioinformatics

A

The application of computational methods to the analysis of large biological data sets

254
Q

Prokaryotes vs eukaryotes: Size of genomes

A

Prokaryotes: relatively small genomes
Eukaryotes: many more but huge variation
- no strong relationship between complexity of eukaryote and size of genome

255
Q

Prokaryotes vs eukaryotes: No of genes

A

Prokaryotes: relatively small no of genes
Eukaryotes: many more no of genes but huge variation
- no strong relationship between complexity of eukaryote and no of genes

256
Q

Gene density

A

No of genes that exist per mega base (Mb)

257
Q

Prokaryotes vs eukaryotes: Gene density

A

Prokaryotes: v efficient genomes - high gene density
Eukaryotes: lower gene density - lots of space within our genome (esp humans)

258
Q

What do most bacterial genomes consist of

A

Genes for proteins, tRNA or rRNA, with the remaining consisting of non-transcribed regulatory regions, e.g. promoeters

259
Q

In eukaryotes, the majority of DNA neither encodes… or ….

A

Protein, nor is transcribed into RNA of known function

260
Q

Humans have ____ more non-coding DNA than bacteria

A

10,000x

261
Q

Where are non-coding DNA regions found in eukaryotes

A

Some within genes (introns) but others aren’t

262
Q

Types of DNA in human genome: Exons

A

Coding part of genome

Very small amount

263
Q

Types of DNA in human genome: Regulatory sequences

A

Once you can produce sufficient no of proteins, it’s when they’re turned on/off that impacts development of organism

264
Q

Types of DNA in human genome: Introns

A

Many are transcribed but don’t get translated

265
Q

Intron shuffling

A

Shuffles which introns are cut out

266
Q

Types of DNA in human genome: Unique non-coding DNA

A

Non-coding region represented only once in genome

267
Q

What is DNA fingerprinting based on

A

Repeats of DNA sequences

268
Q

Number and size of introns in genes

A

Variable

269
Q

Function of introns

A

Not clear, but many are known to be transcribed

270
Q

Pseudogenes

A

Non-functional

271
Q

Transposable elements - steps

A

Start with a retrotransposon
Synthesis of single-stranded RNA intermediate
Reverse transcriptase synthesises 1st DNA strand
DNA pol forms 2nd DNA strand –> mobile copy of retrotransposon
Inserted –> forms new copy of retrotransposon

272
Q

Transposable elements - eukaryotes

A

2 classes;
DNA transposons - cut and paste themselves
Retrotransposons - make an RNA intermediate

273
Q

What are transposable elements

A

Mobile DNA sequences found in genome of all organisms (ubiquitous)

274
Q

Transposable elements: Movement

A

Has certain sequences at end which means it can move into various locations in genome and insert itself

275
Q

Transposable elements - abundant?

A

Abundant in many genomes

e.g. make up ~44% of human DNA

276
Q

Transposable elements - mutation

A

Can often cause mutations by direct insertion into genes

277
Q

Transposable elements - can promote…

A

DNA rearrangements, e.g. chromosome deletions, inversions, duplications

278
Q

Gene duplication can result from…

A

Misaligned recombination during meiosis (unequal crossing over)

279
Q

Gene duplication - process

A

There’s a transposable element on each non-sister chromatid
Since they’re similar in sequence, they line up out of register
Crossing over - one of the genes are moved to other sister chromatid
Results in one sister chromatid with 2 copies and other has none

280
Q

Gene families

A

Groups of genes similar in sequence

281
Q

Gene families - functional?

A

Some remain functional whereas others become non-functional, i.e. pseudogenes

282
Q

Most gene families arise through…

A

Duplication of an existing gene

283
Q

Gene families - functions

A

DNA sequence of genes within family may change –> diff genes may come to have diff functions

284
Q

Gene families - size

A

Some can have only a few genes, some can have many hundreds

285
Q

Why have some genes evolved into tandem arrays

A

Because cells need large amounts of some gene products, e.g. protein

286
Q

Often, the multigene families consist of..

A

Identical tandemly repeated DNA sequences

287
Q

Tandem gene families - examples

A

Genes for histones

rRNA - helps cells makes millions of ribosomes

288
Q

What are tandem gene families

A

Where genes copies are right next to each other

289
Q

Translocations in evolution: Human and chimpanzee

A

Human chromosome 2 is a large metacentric chromosome that resulted from fusion of two acrocentric chromosomes of apes (12 and 13)
Forms telomere-like and centromere-like sequences in human chromosome 2

290
Q

Metacentric

A

Centromere is roughly in middle

291
Q

FOXP2 gene: Mice

A

Wildtype - 2 normal copies
Heterozygous - reduced ability to vocalise
Homozygous - absence of vocalisation

292
Q

FOXP2 gene: Humans and chimpanzees

A

Differ in expression of FOXP2 gene

May explain why humans but not chimpanzees can speak

293
Q

FOXP2 gene: Humans and Neanderthals

A

DNA sequence of gene is similar

Suggests Neanderthals may have been capable of speech

294
Q

Biotechnology

A

The manipulation of organisms or their component parts to make useful products

295
Q

Recombinant DNA technology has launched a revolution in ___________

A

Biotechnology

296
Q

Genetic engineering

A

The in vitro alteration of genetic material and the reintroduction of the altered DNA or RNA into a living organism

297
Q

Main difference between genetic engineering and traditional biotechnology

A

Genetic engineering manipulates DNA or RNA in vitro

298
Q

Genetic engineering vs traditional biotechnology: No of genes

A

Genetic engineering: precise choice of one or a few genes

Selective breeding: new combinations of many genes

299
Q

Genetic engineering vs traditional biotechnology: Type of genes

A

Genetic engineering: genes from any species

Selective breeding: only genes from related species

300
Q

Genetic engineering vs traditional biotechnology: Gene expression

A

Genetic engineering: control of gene expression

Selective breeding: no control

301
Q

Is genetic engineering a substitute for traditional methods

A

No, but it’s a complementary technology

302
Q

Traditional biotechnology: Plant breeders - methods

A

Selective breeding
Cloning
Mutagenesis

303
Q

Traditional biotechnology: Mutagenesis

A

Typically involves using either chemicals or radiation to induce mutations and thus enhance genetic variation

304
Q

Traditional biotechnology: Agriculture

A

Variation in chromosome number has been exploited to create new plant cultivars

305
Q

Cavendish banana

A

A sterile triploid

306
Q

Plants - ease of manipulation

A

Easier to manipulate since they don’t separate their somatic and germ cells

307
Q

Plants - polyploidy

A

Can become polyploidy easily

Often a strong correlation with the size of cells and therefore the size of fruit

308
Q

Genetically engineered food - glyphosate

A

The active chemical in herbicides that inhibits amino acid synthesis

309
Q

Initial vs recent concerns regarding genetically modified plants revolved around…

A

Safety
Public health
Environmental effects

Recent: involves branding of country as ‘genetically engineered-free’ and protecting this image

310
Q

Personalised medicine

A

Where each person’s genetic profile can inform them about diseases and conditions for which they may be at risk

311
Q

Personalised medicine: Many human genetic disorders can now be diagnosed using…

A

PCR and hybridisation / sequencing

312
Q

Personalised medicine: Sequence-specific primers

A

Used to amplify a DNA fragment, which is characterised/sequenced to identify the disease-causing mutation

313
Q

Personalised medicine: What might it lead to

A

Where each individual’s genome is sequenced at birth

314
Q

Genetic test for sickle-cell disease

A
  1. Blood sample from patient
  2. Genomic DNA from WBCs
  3. Region of β-globin gene amplified by PCR
  4. Hybridised with probe
  5. DNA spotted onto binding filters and hybridised with probe
315
Q

Next-generation sequencing: How has it revolutionised DNA sequencing

A

By sequencing multiple strands of DNA simultaneously

Sequences entire genome

316
Q

Next-generation sequencing - steps

A
  1. Genomic DNA is fragmented
  2. Each fragment is isolated with a bead
  3. Using PCR, 10^6 copies of each fragment are made, each attached to magnetic bead by 5’ end
  4. Bead is placed into a well with DNA polymerases and primers
  5. Solutions of each of the 4 nucleotides are added to all wells sequentially then washed off
    Repeat
317
Q

Next-generation sequencing: A chemical technique is used to identify..

A

Which of the four nucleotides is added

318
Q

CRISPR-Cas9 - function

A

Can make targeted deletions, insertions and single nucleotide changes in genomes

319
Q

CRISPR-Cas9: What does it act tgt with

A

A ‘guide RNA’ made from the CRISPR region of bacteria

320
Q

CRISPR-Cas9: What does it cut

A

Any DNA that is exactly complementary to the guide RNA

Cuts both strands –> triggers DNA repair system

321
Q

CRISPR-Cas9: What happens when there’s no undamaged DNA for repair to use as a template

A

Repair system sometimes inserts or removes (random) nucleotides
If cut is directed at a gene, the repair often alters the gene so it no longer functions - ‘knock out’

322
Q

CRISPR-Cas9: Guide RNA

A

Directs protein to exactly the place to be cut

323
Q

CRISPR-Cas9 - formation of Cas9-guide RNA complex

A

Active sites in Cas9 protein can cut DNA
Guide RNA engineered to ‘guide’ Cas9 protein to target gene
Together forms Cas9-guide RNA complex

324
Q

CRISPR-Cas9: The guide RNA can be engineered to be complementary to…

A

A a target gene

325
Q

CRISPR-Cas9: Repairing genes

A

CRISPR-Cas9 can be used to repair a gene, if copies of the functional gene are introduced with the system

326
Q

Gene therapy

A

The introduction of genes into an afflicted individual for therapeutic purposes

327
Q

Gene therapy - aim

A

To insert a normal allele of the defective gene into somatic cells of affected tissue

328
Q

For gene therapy to be permanent…

A

The cells that have the normal allele must be cells that multiply throughout the patient’s life

329
Q

Gene therapy: Prime candidates

A

Bone marrow cells that include stem cells that give rise to all cells of blood and immune system

330
Q

Gene therapy - steps

A
  1. Insert RNA version of normal allele into retrovirus
  2. Let virus infect bone marrow cells that have been removed from patient and cultured
  3. Viral DNA carrying normal allele inserts into chromosome
  4. Inject engineered cells into patient

BIOSCI 101 (4 decks)

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