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Biology > Cellular control > Flashcards

Cellular control Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is transcriptional level control

A

when gene expression is controlled by altering the rate of transcription of genes

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2
Q

what are transcription factors

A

proteins that bind to DNA and switch genes on or off by increasing or decreasing the rate of transcription

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3
Q

what are factors called that start transcription

A

activators

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4
Q

what are factors called that stop transcription

A

repressors

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5
Q

in prokaryotes control of gene expression often involves transcription factors binding to what

A

operons

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6
Q

what is an operon

A

a section of DNA that contains a cluster of structural genes that are all transcribed together as well as control elements and sometimes a regulatory gene

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7
Q

what do structural genes do

A

code for useful proteins such as enzymes

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8
Q

what do the controls meets contain

A

promoters (a DNA sequence located before the structural genes that RNA polymerase binds to and an operator (a DNA sequence that transcription factors bind to

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9
Q

what does the regulatory gene do

A

codes for an activator or repressor

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10
Q

how does the lac operon function when lactose is not present

A

regulatory gene produces lac repressor
this then binds to the operator site where no lactose is present
this blocks transcription as RNA polymerase can’t bind to the promoter

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11
Q

how does the lac operon function when lactose is present

A

lactose binds to the reposer, changing its shape so it can no longer bind to the operator site
RNA polymerase can then begin transcription in structural genes

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12
Q

what is the lac operon, where is it found and what does it do

A

where the genes are found that produce enzymes needed to respire lactose
found in E coli

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13
Q

what is post-transcriptional level control

A

when control of gene expression takes place after post-transcriptional level and mRNA is edited

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14
Q

what are the sections of DNA called that don’t code for amino acids

A

introns

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15
Q

what are the sections of DNA called that do code for amino acids

A

exons

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16
Q

what are mRNA strands called that contain introns and exons

A

primary mRNA transcripts

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17
Q

what happens during ‘splicing’ and where does it take place

A

introns are removed from the primary mRNA and exons are joined together to form mature mRNA
nucleus

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18
Q

some proteins have to be activated after they are made what is an example of this

A

cAMP (post-transcriptional level control)

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19
Q

what is the name for genes that control body plan development

A

Hox genes

19
Q

what are homeobox sequences

A

regions on how genes which are highly conserved so have changed very little during the evolution of different organisms that possess them

19
Q

mutations can be either

A

beneficial or harmful

19
Q

what is substitution

A

one or more bases are swapped for another base

20
Q

what is deletion

A

one or more bases are removed

21
Q

what is insertion

A

one or more bass are added

22
Q

what is a frameshift mutation

A

when insertion or deletion changes the way the rest of the base sequences is read

23
Q

why may a mutation have a neutral effect on an organism

A

a base is changed in the triplet but the amino acid it codes for doesn’t change
the new triplet code codes for a different protein but it is chemical similar to the function of the original one
the mutated triplet code codes for something not involved in protein function

24
Q

what is continuous variation

A

when individuals of a population vary within a range, no distinct categories

25
Q

what is discontinuous variation

A

when individuals vary within distinct categories

26
Q

how does variation in the phenotype occur

A

same genes but different alleles
crossing over and independent assortment
differences in environment

27
Q

what is a polygenic characteristic

A

characteristic influenced by many genes, shows continuous variation

28
Q

what is a monogenic characteristic

A

characteristics influenced by one gene, shows discontinuous variation

29
Q

what is an allele

A

different versions of the same gene

30
Q

what is a gene

A

a sequence of bases on a DNA molecule that codes for a protein

31
Q

what is genotype

A

the alleles an organism has

32
Q

what is a phenotype

A

the characteristics produced by an organisms alleles

33
Q

what does homozygous mean

A

when an organism contains two copies of the same allele

34
Q

what does heterozygous mean

A

if an organism contains two different alleles

35
Q

what are codominant alleles

A

alleles that are both expressed in the phenotype cause neither one is recessive

36
Q

what is a carrier

A

a person carrying an allele which is not expressed in phenotype but can be passed on to offspring

37
Q

what phenotypic ratio would you expect for a monogenic genetic diagram

A

3:1

38
Q

what are dihybrid crosses used for

A

used to show the likelihood of offspring inheriting certain combinations of the two characteristics from particular parents

39
Q

what ratio do you expect from a dihybrid cross

A

9:3:3:1

40
Q

what does it mean if a characteristic is sex linked

A

the alleles that code for that characteristic are found on the sex chromosome

41
Q

what is epistasis

A

when the allele of one gene masks the expression of the alleles of other genes

42
Q

what is an autosome

A

a chromosome that is not a sex chromosome

43
Q

what ratio would you expect for a dominant epistatic allele cross diagram

A

12:3:1

44
Q
A

Biology (25 decks)

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