Unit 4 - Genetic information, variation and relationships between organisms Flashcards

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1
Q

Gene mutation

A

a change to one or more nucleotide bases in DNA that could result in a change in genotype which may be inherited

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2
Q

Autosome

A

a chromosome which is not a sex chromosome

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3
Q

Homologous chromosomes

A

a pair of chromosomes, one maternal and one paternal, they have the same gene loci so determine the same features but they are not necessarily identical as they have different alleles. they are capable of pairing during meiosis

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4
Q

Codon

A

a sequence of three adjacent nucleotides in mRNA that codes for one amino acid

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5
Q

Anticodon

A

a sequence of three adjacent nucleotides on tRNA that is complementary to a particular codon on a mRNA molecule

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6
Q

Chromosome

A

a thread like structure made of protein and DNA by which hereditary information is physically passed from one generation to the next

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7
Q

Allele

A

different forms of a gene with different base sequences and different codes

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8
Q

Diploid

A

cell or nucleus containing pairs of homologous chromosomes

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9
Q

Haploid

A

cell or nucleus containing single, unpaired chromosomes

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10
Q

Nucleotides

A

complex chemicals made of an organic, nitrogenous base, a sugar and a phosphate. They are the basic units of which DNA and RNA are made

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11
Q

DNA helicase

A

enzyme that acts on a specific region on the DNA molecule to break the hydrogen bonds between the bases causing the two strands to separate and expose the nucleotide bases

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12
Q

RNA polymerase

A

enzyme that joins together nucleotides to form messenger RNA during transcription

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13
Q

Transcription

A

formation of mRNA molecules from the DNA that makes up a particular gene. first stage of protein synthesis

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14
Q

Polymerases

A

group of enzymes that catalyse the formation of polymers from monomers

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15
Q

ATP

A

nucleotide found in all living organisms, which is produced during respiration and is important in the transfer of energy

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16
Q

Chromatid

A

one of the two strands of a chromosomes that are joined together by a single centromere prior to cell division

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17
Q

Exons

A

portions of DNA within a gene that codes for proteins. they are joined together during splicing

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18
Q

Introns

A

portions of DNA within a gene that do not code for a polypeptide. they are removed from the pre-mRNA after transcription in splicing

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19
Q

Histones

A

proteins, which together with DNA, make up the chromosomes of eukaryotic cells

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20
Q

Gamete

A

reproductive (sex) cell that fuses with another gamete during fertilisation

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21
Q

Gene

A

section of DNA on a chromosome that controls a feature by coding for formation of one or more specific polypeptides or functional RNA

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22
Q

Translation

A

the latter part of protein synthesis when the mRNA is used as a template to which complementary tRNA molecules attach and the amino acids link to form a polypeptide

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23
Q

Chromatin

A

the material that makes up chromosomes. it consists of DNA and the histone proteins

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24
Q

Splicing

A

the process by which base sequences corresponding to the introns are removed and the functional exons are joined together

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25
Q

DNA replication

A

the process in which the double helix of a DNA molecule unwinds and each strand acts as a template on which a new strand is constructed

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26
Q

Crossing over

A

the process where a chromatid breaks during meiosis and rejoins to the chromatids of its homologous chromosome so that their alleles are exchanged

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27
Q

Locus

A

the specific linear position of a particular gene on a certain chromosome

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28
Q

Human genome

A

the complete set of genes in a cell, including those in mitochondria and/or chloroplasts

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29
Q

Mitosis

A

the type of nuclear division in which the daughter cells have the same number of chromosomes as the parent cell

30
Q

Meiosis

A

the type of nuclear division where the number of chromosomes is halved

31
Q

tRNA

A

the type of RNA made of around 80 nucleotides and has an anticodon which is complementary to a section of mRNA. each molecule is specific to one amino acid

32
Q

mRNA

A

the type of RNA that is a long strand arranged in a single helix and its base sequence is determined by the sequence of bases on a length of DNA

33
Q

DNA polymerase

A

enzyme that joins DNA nucleotides together in a condensation reaction (forming phosphodiester bonds) during DNA replication

34
Q

Proteome

A

the full range of proteins produced by the genome

35
Q

Describe the process of transcription

A

DNA helicase breaks the hydrogen bonds between bases and causes the DNA helix to unwind
only one strand acts as a template
free mRNA nucleotides align opposite exposed complementary DNA bases
RNA polymerase bonds together the the RNA nucleotides

36
Q

Describe the process of translation

A

mRNA attaches to ribosome at the start codon
the tRNA molecule with the complementary anticodon to the start codon aligns opposite the mRNA
ribosomes moves along the mRNA molecule
the two amino acids that have been delivered by the tRNA are joined by a peptide bond
this is catalysed by RNA polymerase and requires ATP
this continues until the ribosome reaches the stop codon
ribosome detaches

37
Q

What happens to the polypeptide after translation?

A

goes to the Golgi body for folding and modification

38
Q

What is genetic diversity?

A

the total number of different alleles in a population

39
Q

Describe natural selection

A

random mutation of alleles = new alleles
new allele can give advantage
better adapted so more likely to survive
reproductive success
pass on new allele to offspring
allele frequency increases

40
Q

Population definition

A

group of individuals of the same species that live in the same place and can interbreed

41
Q

Species definition

A

a population of the same organisms that breed to produce fertile offspring

42
Q

Genetic diversity definition

A

the total number of different alleles in a population

43
Q

Selection definition

A

process whereby organisms that are better adapted to their environment survive and breed

44
Q

What are the two types of selection?

A

directional and stabilising

45
Q

Phenotype definition

A

observed characteristics of an organism

46
Q

What is directional selection?

A

the alleles of an extreme type are selected

47
Q

What is stabilising selection?

A

the alleles near the mean and selected are favoured

48
Q

What is the purpose of courtship behaviour?

A
  • recognition of individuals of same species
  • identify a mate
  • form a pair bond
  • synchronise mating
  • being able to breed
49
Q

What is taxonomy?

A

the study of the principles behind classification

50
Q

What is artificial classification?

A

grouped according to visible differences (analogous characteristics)

51
Q

What is phylogenetic classification?

A

based on evolutionary relationships between organisms and their ancestors (homologous characteristics)

52
Q

What is meant by a hierarchy?

A

larger groups which have smaller groups within them, there is no overlap

53
Q

Biodiversity definition

A

number and variety of living organisms in a particular area

54
Q

Species diversity definition

A

number of different species and individuals within a community

55
Q

Species richness definition

A

the number of different species in a particular area at a given time

56
Q

What are the modern methods of classification?

A
  • DNA nucleotide sequence of entire genomes
  • DNA nucleotide sequence of certain genes
  • RNA nucleotide sequences
  • amino acid sequences of shared proteins
  • the antigens found on cells
57
Q

Sampling definition

A

taking measurements of individuals selected from a population

58
Q

Which protein is often used for comparison?

A

cytochrome c

59
Q

Define mutagenic agent

A

a factor that increases the rate of mutations

60
Q

allele frequency

A

the number of times an allele occurs within the gene pool

61
Q

binomial naming

A

internationally recognised method of naming organisms using the genus and species names

62
Q

conservation

A

method of maintaining ecosystems and the living organisms that occupy them

63
Q

continuous variation

A

variation in which organisms do not fall into distinct categories but show gradations from one extreme to the other

64
Q

courtship behaviour

A

the behaviour by which different species identify, attract and select their partners for reproduction

65
Q

discontinuous variation

A

variation shown when the characteristics of organisms fall into distinct categories

66
Q

hierarchy

A

the taxonomic classification of living organisms in successive levels of complexity. small groups within large groups but there are no overlaps between the groups

67
Q

index of diversity

A

calculation that determines the biodiversity in an area based on the number of different species and the number of individuals of each species

68
Q

interspecific variation

A

differences between organisms of different species

69
Q

intraspecific variation

A

differences between organisms of the same species

70
Q

Describe the process of crossing over and explain how it increases genetic
diversity.

A
  • homologous pairs of chromosomes associate
  • chiasma form
  • alleles are exchanged
  • producing new combination of alleles
71
Q

Describe how one amino acid is added to a polypeptide that is being
formed at a ribosome during translation.

A

tRNA brings specific amino acid to ribosome
anticodon binds to codon
amino acids join by condensation reaction forming a peptide bond

72
Q

Describe how a polypeptide is formed by translation of mRNA.

A

mRNA attaches to ribosome
anticodons bind to complementary codons
tRNA brings a specific amino acid
amino acids join by peptide bonds
tRNA released
ribosome moves along the mRNA to form the polypeptide