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Biology > 4) Genetic Information, Variation, and Relationships Between Organisms > Flashcards

4) Genetic Information, Variation, and Relationships Between Organisms Flashcards

- DNA, genes, and protein synthesis - Genetic Diversity - Biodiversity

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1
Q

in terms of their purpose, what is the difference between RNA and DNA?

A

DNA holds genetic information, whereas RNA transfers genetic information from DNA to ribosomes

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2
Q

what are ribosomes made of?

A

rRNA and proteins

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3
Q

what are the components of DNA nucleotide?

A

deoxyribose
a phosphate group
an organic base

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4
Q

which bases are purine bases? why?

A

adenine and guanine
they have double ring structures

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5
Q

what are the components of an RNA nucleotide?

A

ribose
a phosphate group
an organic base

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6
Q

which organic bases are pyrimidines? why?

A

thymine, uracil, and cytosine
they have single ring structure

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7
Q

which of the bases can a DNA nucleotide have?

A

adenine, thymine, cytosine, guanine

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8
Q

which of the bases can an RNA nucleotide have?

A

adenine, uracil, cytosine, guanine

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9
Q

how are nucleotides joined? give the bond and reaction

A

by phosphodiester bonds formed in condensation reactions

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10
Q

what bonds join complementary bases?

A

hydrogen bonds

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11
Q

what is the genetic code?

A

the order of bases on DNA, which consists of triplets of bases

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12
Q

what is a codon?

A

a sequence of 3 bases on mRNA that codes for a specific amino acid

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13
Q

what is a gene?

A

a length of DNA on a chromosome that codes for a sequence of amino acids in a polypeptide chain

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14
Q

what is a locus?

A

the location of a gene on a chromosome

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15
Q

what are introns and exons?

A
  • introns are non-coding sections of DNA
  • exons are coding sections
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16
Q

how many different amino acids are there?

A

20

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17
Q

how many possible triplets are there?

A

64

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18
Q

what does non-overlapping mean?

A

each base in a sequence is read once and is only part of one triplet

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19
Q

what does degenerate mean, in relation to the genetic code?

A

more than one triplet codes for the same amino acid

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20
Q

what is the advantage of the genetic code being degenerate?

A

reduces the number of mutations

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21
Q

what are the differences between eukaryotic DNA and prokaryotic DNA?

A

EUKARYOTIC
- long and linear
- associated with histones

PROKARYOTIC
- short and circular
- not associated with proteins

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22
Q

how many chromosomes are there in each human body cell?

A

46

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23
Q

how are chromosomes arranged in each cell?

A

in homologous pairs

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24
Q

what is a homologous pair?

A

two chromosomes that carry the same genes at the same locus

25
Q

why are the chromosomes in a homologous pair not identical?

A

because they can carry different alleles of the same gene

26
Q

which chromosome determines sex?

A

23

27
Q

what is an allele?

A

an alternative version of the same gene

28
Q

what are the two stages of protein synthesis?

A

transcription and translation

29
Q

what is transcription?

A

the formation of pre-mRNA in eukaryotes and mRNA in prokaryotes from a section of the template strand of DNA

30
Q

where does transcription occur?

A

in the nucleus

31
Q

during what process is mRNA made?

A

transcription

32
Q

what is the role of mRNA?

A

carries the genetic code from the DNA to the ribosomes, where it’s used to make a protein

33
Q

describe the structure of mRNA

A

single polynucleotide strand

34
Q

what are groups of 3 adjacent bases called in mRNA?

A

codons

35
Q

what process is tRNA involved in?

A

translation

36
Q

what is the role of tRNA?

A

carries the amino acids, used to make proteins, to the ribosomes

37
Q

describe the structure of tRNA

A

single polynucleotide strand folded into a clover shape

38
Q

what bonds hold tRNA into its clover shape?

A

hydrogen bonds between specific base pairs

39
Q

what do tRNA molecules have at each end?

A

an anticodon and an amino acid binding site

40
Q

what is an anticodon?

A

a sequence of 3 nucleotide bases at one end of a tRNA molecule that is specific to an mRNA codon

41
Q

where does transcription take place in eukaryotic and prokaryotic cells?

A
  • eukaryotic = in the nucleus
  • prokaryotic = in the cytoplasm
42
Q

where does translation occur?

A

at the ribosomes in the cytoplasm

43
Q

describe the process of translation

A
  • mRNA attaches to a ribosome and tRNA collects amino acids from cytoplasm and carries them to the ribosome
  • tRNA attaches to mRNA by complementary base pairing, two molecules of tRNA attach at a time
  • amino acids attached to two tRNA molecules join by a peptide bond and tRNA molecules detach from the amino acids to leave them behind
  • process repeats leading to the formation of a polypeptide chain until a stop codon is reached
44
Q

what is a genetic mutation?

A

any change in the base sequence or quantity of DNA

45
Q

what can a change in the base sequence of a gene result in?

A

a change to the sequence of amino acids

46
Q

why does a genetic mutation not always lead to a change in the amino acid sequence?

A

because the genetic code is degenerate (more than one triplet codes for the same amino acid)

47
Q

what are the types of genetic mutation?

A
  • substitution
  • deletion
  • addition
  • inversion
  • duplication
  • translocation
48
Q

what are the two kinds of mutations that can occur in chromosomes?

A

polyploidy and non-disjunction

49
Q

what is polyploidy?

A

changes that occur in the whole set of chromosomes so that an individual has three or more sets of chromosomes instead of two

50
Q

what is non-disjunction?

A

when chromosomes fail to separate correctly in meiosis, resulting in the gametes and therefore any zygotes formed having one more or fewer chromosome than they should

51
Q

how many daughter cells are produced by meiosis?

A

4

52
Q

are daughter cells produced by meiosis genetically identical or unique?

A

genetically unique

53
Q

how many chromosomes do gametes have in relation to the parent cell?

A

half the number

54
Q

what is the role of meiosis?

A

production of haploid gametes

55
Q

why must gametes be haploid?

A

so that when two gametes fuse, the zygote produced is diploid

56
Q

by what two ways is genetic variation achieved?

A
  • independent segregation
  • crossing over
57
Q

when does independent segregation occur?

A

during meiosis 1

58
Q
A
59
Q

Describe the process of meiosis

A

1) DNA unravels and replicates so there are 2 copies of each chromosome
2) DNA condenses to form double-armed chromosomes each made from a sister chromatids
3) meiosis 1 - chromosomes arrange themselves into homologous pairs
4) Homologous pairs are separated, halving the chromosome number
5) meiosis 2 - each pair of sister chromatids, that make up each chromosome, are separated
6) 4 genetically different (from each other) haploid daughter cells are produced

Biology (8 decks)

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