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biology > Genetic Diversity And Adaptation > Flashcards

Genetic Diversity And Adaptation Flashcards

1
Q

Define mutation

A

Change to quantity or sequence of bases

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2
Q

Define gene mutation

A

Change to base sequence of DNA

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3
Q

When are gene mutations most likely to occur?

A

Synthesis phase

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4
Q

What are the types of gene mutations?

A

Substitution

Deletion

Addition

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5
Q

Describe the difference between the effects of a Deletion and substitution mutation

A

Deletion causes frame shift so all Amino acids change

Substitution changes one triplet so one Amino acid changed

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6
Q

Describe how deletion can lead to a non functional protein

A 
Frame shift
Diff triplets
Diff codons and anti codons
Diff Amino acids in polypeptide
Change to ionic hydrogen and disulphide bond placement
Change to tertiary structure
Change to shape and function
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7
Q

Define carcinogen

A

A substance that increases the likelihood of mutations occuring

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8
Q

Name carcinogens

A

UV radiation

Toxic chemicals

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9
Q

Define chromosome mutation

A

Change to structure or number of chromosomes

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10
Q

What are the two types of chromosome mutations

A

Change to whole set of chromosomes

Change to one pair of chromosomes

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11
Q

Name the effects of change to a whole set of chromosomes and why it occurs

A

Polyploidy

Sister chromatids fail to seperate

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12
Q

Name the effects of change to a one pair of chromosomes and why it occurs

A

Non-disjunction

Homologous pairs fail to seperate during meisosis

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13
Q

Why is mitosis important

A

For genetic variation

Allow continuity of diploid number between generations (prevent doubling)

Allow diploid no to be restored upon fertilisation

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14
Q

What occurs to chromosomes during meiosis??

A

Nuclear envelope disintegrates and chromosomes condense and pair up (crossing over) and spindle fibres develop from centrioles

Spindle fibres attach to centromeres and align pairs at equator of cell. Independent segregation.

Spindle fibres contract and pull homologous chromosomes apart to opposite poles

Spindle fibres disintegrate and nuclear envelope forms, cytokinesis

Occurs again but this time sister chromatids are. Pulled apart and centromeres divide

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15
Q

When does the number of chromosomes half in meiosis (1 or 2)

A

1

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16
Q

Define I dependent segregation

A

Random allocation of chromosomes to gametes

17
Q

Define crossing over/recombination

A

Chromatids on homologous pairs intertwine and pressure causes breakages and recombination or alleles.

Alleles exchanged between pairs

18
Q

What is the main source of genetic variation in meiosis

A

Crossing over and recombination

19
Q

How do you calculate the number of possible chromosome combinations in gametes due to independent segregation only?

A

2^n

n= haploid no

20
Q

How do you calculate the number of possible chromosome combinations in zygotes due to independent segregation only?

A

(2^n)^2

n=haploid no

21
Q

Why are their a variety of different organisms

A

Difference in alleles and environment

22
Q

Define genetic diversity

A

Variety of different alleles present in population

23
Q

Why does increased genetic diversity mean a more stable community

A

More chance that an individual will posses

advantageous alleles so survive and reproduce to carry on species

24
Q

Define population.

A

All organisms of a species in the same habitat at the same time

25
Q

Why does natural selection occur

A

Due to genetic diversity and selection pressures

26
Q

How does natural selection occur

A 
Variety of alleles in gene pool
Some have advantageous alleles so are more likely to survive and reproduce
Pass on alleles
Occurs over many generations
Allele frequency increases
27
Q

Define selection

A

Process by which better adapted organisms are more likely to survive and reproduce

28
Q

Define polygenes

A

Describes characteristics that are controlled by multiple genes

29
Q

What are the types of selection

A

Directional and stabalising

30
Q

What’s the difference between the different types of selection

A

Directional:
Change in environment
Change to phenotype
Extremes favoured

Stabalising :
Stable environment
No change to environment
Less variation
Average favoured
31
Q

Give examples of each type of selection

A

Directional= antibiotic resistance

Birth weight = Stabalising

32
Q

Describe what occurs to mean and SD/variation in directional selection

A

Mean changes

SD same

33
Q

Describe what occurs to mean and SD/variation in Stabalising selection

A

Mean = same

SD = smaller

34
Q

What types of adaptions may occur

A

Anatomical
Physiological
Behavioural

35
Q

Why might logs be used in Graphs

A

Make changes easier to see

biology (28 decks)

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