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MOLECULAR BIO > CH.5 PPT > Flashcards

CH.5 PPT Flashcards

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Biology 101 flashcards
1
Q

the number of genes in bacterial and archaeal (prokaryotes) is proportional to

A

genome size (more genes = bigger genome size)

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2
Q

there is no clear relationship between the number of ______ and ____ of an organism/size of genomes in _____

A

number of genes and complexity in eukaryotes (no correlation)

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3
Q

which taxonomic group has the highest correlation between the number of genes and the size of the genome

a. plants
b. yeast
c. prokaryotes
d. invertebrate animals
e. vertebrate animals

A

c. prokaryotes

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4
Q

proportion of unique genes ____ and proportion of gene families ____ with _____ genome size

A

unique genes decreases and gene families increases with increasing genome size

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5
Q

more complex organism and bigger genome size = ?

A

higher proportion of gene families

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6
Q

what are orthologs

A

related genes in different species

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7
Q

what are orthologous genes

A

many genes that are common to many (or all) organisms

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8
Q

iCLICKER: in a complex organism such as humans, would you expect to have a higher proportion of gene families compared to yeast?

A. Yes
B. No

A

A. Yes (humans are more complex than yeast)

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9
Q

the human genome has _____ genes than originally expected

A

fewer

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10
Q

only 1% of the human genome consists of

A

exons

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11
Q

exons comprise about ____% of each gene

A

5%

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12
Q

genes (exons + introns) comprise about ____% of the genome

A

25%

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13
Q

the human genome has about _______ genes

A

20,000 genes

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14
Q

repeated sequences (present in more than one copy) account for more than ______% of human genome

A

50%

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15
Q

what do the bulk of repeated sequences consist of

A

copies of nonfunctional transposons

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16
Q

what is the largest component of the human genome consist of

A

transposons (45%)

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17
Q

there are many duplications of

A

large chromosome regions in the human genome

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18
Q

are all genes essential?

A

NO

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19
Q

what does it mean when two or more genes are redundant?

A

a mutation in any one of them might not have detectable effects (genes are overtaking a role that has been removed)

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20
Q

iCLICKER: in C. elegans, what fraction of genes are essential for survival

a. 0%
b. 1%
c. 10%
d. 50%
e. 100%

A

c. 10%

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21
Q

what is redundancy

A

when we are able to knock genes out and the organism is fine without them because a gene is overtaking its role

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22
Q

what is a synthetic lethal mutation

A

a strain in which a double mutation is lethal while each mutation on its own is not (can make single or double mutations)

23
Q

in any particular cell, most genes are expressed at a ?

A

low level

24
Q

only a small number of genes, whose products are highly specialized for the cell type are…

A

highly expressed

25
Q

what is it mean when a gene is highly expressed?

A

that gene is highly important for the cell and cell function

26
Q

what happens to mRNAs that are expressed at low levels

A

they overlap extensively when different cell types are compared

27
Q

what is a housekeeping gene

A

a gene that is (theoretically) expressed in all cells because it provides basic functions needed for sustenance of all cell types

28
Q

abundantly expressed mRNAs are usually

A

specific for the cell type

29
Q

there is no true “universal” housekeeping gene - several may be used, or they should be selected carefully based on ?

A

cell/tissue type and experimental conditions

30
Q

iCLICKER: most genes of an organism

a. show unregulated expression
b. are expressed at high levels
c. are never expressed
d. are expressed only in a single cell type
e. are expressed at low levels

A

e. are expressed at low levels

31
Q

what is DNA microarray

A

technology that allows a snapshot to be taken of the expression of the entire genome in a yeast cell

32
Q

what is the probability of a mutation influenced by

A

the likelihood that the particular error will occur and the likelihood that it will be repaired

33
Q

what is a synonymous mutation

A

a change in DNA sequence in a coding region that does NOT alter the amino acid sequence that is encoded

34
Q

what is a non synonymous mutation

A

a change in DNA sequence in a coding region that alters the amino acid that is encoded

35
Q

what is a neutral mutation

A

mutation that has NO effect on the phenotype of the organism

36
Q

what is negative selection

A

if a nonneutral mutation negatively affects the phenotype, selection may eliminate this mutation

37
Q

what is positive selection

A

if a nonneutral mutation confers an advantage, selection may propagate this mutation

38
Q

iCLICKER: in a particular DNA sequence, nonsynonymous substitutions occurring at a lower rate than synonymous substitutions would be evidence for

a. neutral evolution
b. negative selection
c. genetic hitchhiking
d. positive selection
e. mutational basis

A

b. negative selection

39
Q

what is divergence

A

the difference between two genes

40
Q

the divergence between any pair of sequences is proportional to

A

the time since they shared a common ancestor

41
Q

what is a molecular clock

A

measures the accumulation of substitutions at an approximately constant rate during the evolution of a particular protein coding gene

42
Q

synonymous mutations do NOT alter the amino acid BUT they affect…

A

gene expression, rate of translation, protein folding, etc. and therefore the phenotype of an organism (not as bad as non synonymous)

43
Q

T/F: Synonymous mutations have no effect on the protein product

A

FALSE

44
Q

what are pseudogenes

A

do not produce polypeptides and may be nonfunctional or have an altered (regulatory) function

45
Q

what is abundance

A

average number of mRNA molecules per cell

46
Q

what is abundant mRNA

A

consists of a small number of individual species, each present in a large number of copies per cell

47
Q

when does genome duplication occur

A

when polyploidization increases
the chromosome number by a multiple of two

48
Q

what is a haploid

A

a single set of unpaired
chromosomes.

49
Q

what is a diploid

A

containing two complete sets of
chromosomes, one from each parent.

50
Q

what is a tetraploid/hexaploid

A

containing four/six
complete sets of chromosomes.

51
Q

aneuploidy occurs when

A

there is an abnormal number of chromosomes (e.g., 45 or 47 in humans).

52
Q

what is autopolyploidy

A

Polyploidization resulting from mitotic or meiotic errors within a species.

53
Q

what is allopolyploidy

A

Polyploidization resulting from hybridization between two different but reproductively compatible species

54
Q

iCLICKER: canvendish bananas have 3 copies of each autosome. there are therefore known as a _____ organism.

a. haploid
b. diploid
c. triploid
d. tetraploid
e. aneuploid

A

c. triploid

MOLECULAR BIO (6 decks)

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