DNA, genes and chromosomes Flashcards

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1
Q

what does prokaryote mean

A

before the nucleus

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2
Q

prokaryotic DNA circular or linear

A

circular

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3
Q

what DNA do prokaryotes contain

A

a single, circular chromosomal DNA molecules

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4
Q

what is the single, circular chromosomal DNA in prokaryotes sometimes reffered to as

A

nucleoid

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5
Q

what are plasmids

A

very small circular DNA molecules

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6
Q

how many genes do plasmids contains

A

a few

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7
Q

why are plasmids used

A

more accessible for proteins requires for a gene expression and therefore contain genes that are requires often, quickly and in emergencies

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8
Q

where are genes for antibiotic resistance found

A

plasmids

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9
Q

prokaryotic DNA protein association

A

not associated with any proteins

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10
Q

eukaryotic DNA protein association

A

histone proteins

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11
Q

what are chromosomes (eukaryotic) made of

A

one long, condensed DNA molecules associated with histone proteins

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12
Q

role of histone proteins

A

organise and condense the DNA tightly to fit into the nucleus

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13
Q

what are the other proteins (not histone) used for in eukaryotic chromosomes

A

enzymes used in copying and repairing DNA

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14
Q

what is chromatin

A

tightly coiled combination of DNA and proteins

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15
Q

what are chromatids and chromosomes made of

A

chromatin

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16
Q

what happens during s phase of interphase

A

the DNA replicates to create two identical strands of DNA called chromatids joined together by a narrow region called the centromere

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17
Q

what are sister chromatids

A

two chromatids that make up the double structure of a chromosome

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18
Q

why is important sister chromatids are identical

A

key to cell division as one chromatid goes into one daughter cell and one to the other during mitosis ensuring daughter cells are genitally identical

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19
Q

what is a chromatid made of

A

a very long, condensed DNA molecules, which is made up of a series of genes

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20
Q

how are ends of the chromatids in the chromosome

A

sealed with protective structures called telomeres

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21
Q

what DNA is mitochondrial and chloroplast DNA most similar to

A

prokaryotic

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22
Q

what is mitochondria and chloroplast DNA like

A

short, circular and not associated with proteins

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23
Q

Mitochondria + chloroplast DNA

A

small circular pieces of DNA

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24
Q

what organelles contains their own DNA

A

mitochondria and chloroplast

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25
Q

what is a gene

A

base sequence of DNA that codes for the amino acids sequence of a polypeptide or functional RNA molecule

26
Q

how is mRNA used

A

base sequences on mRNA molecules are used by ribosomes to form polypeptide chains

27
Q

how is tRNA used

A

amino acids are carried to the ribosome by tRNA molecules

28
Q

how is rRNA used

A

rRNA molecules form part of the structure of ribososmes

29
Q

what does shape and behavior of a proteins molecule depend on

A

the exact sequence of amino acids (primary structure of the protein)

30
Q

what do genes in DNA molecules control

A

protein structure as they determine they exact sequence of amino acids joined together when proteins are synthesied in the cell

31
Q

what is DNA essential for

A

cell survival

32
Q

what does every chromosome consist of

A

a long DNA molecules and its associated protein

33
Q

what does every chromosome consist of

A

a long DNA molecule that codes for several different proteins

34
Q

what is a locus

A

position of a gene on a chromosome

35
Q

what can different alleles of a gene have

A

slightly different nucleotide sequence but still occupy the same locus on the chromosome

36
Q

gene

A

base sequence of DNA that codes for the amino acid sequence of polypeptide or functioning DNA

37
Q

3 features of prokaryotic DNA

A

short, circular and not associated with proteins

38
Q

3 features of eukaryotic DNA

A

very long, linear and associated with histone proteins

39
Q

what is the DNA nucleotide base code found within the gene

A

a triplet code

40
Q

how many bases code for 1 amino acid

A

3

41
Q

triplets of bases known as

A

codons

42
Q

how many amino acids are there

A

20

43
Q

what are start and stop signals

A

triplets of bases which tell the cell where the individual genes starts and stop

44
Q

what do start and stop signals ensure

A

the cell reads the DNA correctly and can produce the correct sequences of amino acids that require it to function properly

45
Q

how many triplets are possible

A

64

46
Q

what is degenerate genetic code

A

multiple codons code for the same amino acid

47
Q

what can degenerate code limit

A

effect of mutations

48
Q

what is universal genetic code

A

all organisms use the same code (few exceptions)

49
Q

what does universal code mean

A

same codons code for same amino acids in all living things so genetic information is transferable between species)

50
Q

3 features of genetic code

A

non-overlapping, degenerate and universal

51
Q

what does genetic code being non-overlapping mean

A

each base triplet is read in sequence, separate from specific amino acid before and after it. base triplets don’t share their bases

52
Q

which type of cell is non-coding DNA found in

A

eukaryotic

53
Q

what is non-coding DNA

A

does not code for any amino acids

54
Q

where can non-coding DNA be found

A

between genes and within genes

55
Q

how is non-coding DNA found between genes

A

as non-coding multiple repeats which means they contain the same base sequences repeated multiple times

56
Q

what is the non-coding DNA within genes called

A

introns

57
Q

how are exons separated

A

one or more introns

58
Q

what are coding sections of DNA called

A

exons

59
Q

what is transcribed in transcription

A

they whole gene (introns and exons) to produce pre-mRNA molecules

60
Q

what is produced in transcription

A

pre-mRNA molecules

61
Q

what happens before pre-mRNA leaves the nucleus

A

splicing

62
Q

what is splicing

A

removing the introns (non-coding sections) and joining together the exons (coding sections)