Topic 4 Biology Flashcards

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1
Q

What is a mutagenic agent?

A

A factor that increases the rate of mutations.

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1
Q

What is disjunction?

A

In meiosis chromosomes not separated

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2
Q

Other than mutations what is one way genetic variation is increased within a species.

A

Random fusion of gametes produces new allele combinations.

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3
Q

Why are gametes genetically different?

A

Crossing over or independent segregation

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4
Q

Why does having too many chromosomes make something sterile.

A

Too many chromosomes so homologous chromosomes do not pair
So no meiosis

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5
Q

What is a gene mutation

A

A change in the base sequences of DNA which results in formation of a new allele

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6
Q

Explain how the chromosome number is halved during meiosis

A

The homologous chromosomes pair one of each pair goes to each daughter cell

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7
Q
A
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8
Q

What is the process of crossing over and how does it increase genetic diversity?

A

Homologous pairs of chromosomes associate
Chiasma forms
Equal lengths of chromatids exchanged
Producing new combinations of alleles.

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9
Q

Describe how mRNA is formed by transcription in eukaryotes

A

H bonds between DNA bases break
One DNA strand acts as template
RNA nucleotides align by complementary base pairing.
In RNA U pairs with A.
RNA polymerase joins adjacent RNA by phosphodiester bonds

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10
Q

Describe how a polypeptide is formed by translation of mRNA

A

mRNA attached to ribosomes
anticodons bind to complementary codons
tRNA brings specific AA which are then joined together by peptide bonds with use of ATP
TRNA released
Ribosome moves along mRNA to form polypetide

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11
Q

What is the fixed position occupied by a gene on a dna molecule

A

Locus/loci

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12
Q

What is an exon

A

Base sequence coding for a polypeptide

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13
Q

How is a phosphodiester bond formed between two nucleotides in dna

A

Condensation reaction between phosphate and deoxyribose catalysed by dna polymerase

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14
Q

Protein associated with dna in chromosome

A

Histone

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15
Q

3 differences between prokaryotic and eukaryotic dna

A

Euk
Linear
histones
No plasmids

Pro
Circular
No histones
Plasmids

16
Q

What is a homologous pair of chromosomes

A

Two chromosomes that carry same gene

17
Q

What term is used to describe method of naming organisms

A

Binomal

18
Q

What is a hierarchy

A

Smaller groups within larger groups no overlap between groups

19
Q

What are 3 comparisons of genetic diversity that scientists can use

A

DNA base sequencing
Base sequence of mRNA
AA sequence of proteins

20
Q

Two reasons other than hunting why populations may show very low levels of genetic diversity

A

Inbreeding
Population started small

21
Q

What is directional selection?

A

One extreme allowed to breed

22
Q
A