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topic 4 Flashcards

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1
Q

What is a gene?

A

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

Includes rRNA and tRNA

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2
Q

Define 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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3
Q

What is chromatin?

A

The material that makes up chromosomes, consisting of DNA and the protein histone

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4
Q

What is an autosome?

A

A chromosome which is not a sex chromosome

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5
Q

What is the genetic code?

A

The sequence of triplets of nucleotides (codons) in DNA which determines the sequence of amino acids in an organism’s proteins

It is degenerate, non-overlapping, universal, and has start and stop codons

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6
Q

What does it mean that the genetic code is degenerate?

A

A single amino acid may be coded for by more than one triplet code

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7
Q

Explain non-overlapping in the context of the genetic code.

A

Each base appears in only one triplet – each base is only read once

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8
Q

What is meant by the genetic code being universal?

A

The genetic code is the same in all organisms, providing indirect evidence for evolution

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9
Q

What are histones?

A

Proteins that, together with DNA, make up the chromosomes of eukaryotic cells

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10
Q

Define chromatid.

A

Each of the two thread-like strands into which a chromosome divides, joined together by a single centromere prior to cell division

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11
Q

What is a locus?

A

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

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12
Q

What are alleles?

A

Alternative forms of a particular gene with different base sequences, and therefore different codes

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13
Q

Define protein synthesis.

A

The process by which the genetic code codes for proteins in the cell, involving transcription and translation

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14
Q

What is a genome?

A

The complete set of genetic material present in a cell or an organism

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15
Q

What is the human genome?

A

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

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16
Q

Define proteome.

A

The full range of proteins produced by the genome, sometimes referred to as the complete proteome under specific conditions

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17
Q

What is transcription?

A

Formation of messenger RNA molecules from the DNA that makes up a particular gene; the first stage of protein synthesis

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18
Q

What enzyme is responsible for joining nucleotides to form mRNA during transcription?

A

RNA Polymerase

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19
Q

What are nucleotides?

A

Complex chemicals made up of an organic base, a sugar, and a phosphate; the basic units of nucleic acids DNA and RNA

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20
Q

What is mRNA?

A

The type of RNA that is a long strand arranged in a single helix, with its base sequence determined by a length of DNA

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21
Q

Define triplet.

A

A sequence of three bases in DNA

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22
Q

What is the template strand?

A

The strand of DNA used during transcription to make mRNA, running in a 3’ to 5’ direction

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23
Q

What is a codon?

A

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

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24
Q

What is an intron?

A

Portions of DNA within a gene that do not code for a polypeptide and are removed from pre-mRNA after transcription

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25
What is an exon?
Portions of DNA within a gene that code for proteins and are joined together during splicing
26
Define splicing.
The process of removing introns and joining functional exons together
27
What is translation?
The latter part of protein synthesis when mRNA is used as a template for tRNA molecules to link amino acids and form a polypeptide
28
What is tRNA?
Type of RNA made of around 80 nucleotides with an anticodon complementary to mRNA, specific to one amino acid
29
Define anti-codon.
A sequence of three adjacent nucleotides on tRNA that is complementary to a codon on mRNA
30
What is a ribosome?
An organelle made of rRNA and proteins that synthesizes polypeptides by binding to mRNA and using tRNA
31
What is a polypeptide?
A polymer consisting of a large chain of amino acids bonded together by peptide bonds
32
What is a gene mutation?
A change to one or more nucleotide bases in DNA that could result in a change in genotype which may be inherited
33
Define substitution mutation.
If a nucleotide is changed in the DNA sequence
34
What is a nonsense mutation?
If the base change results in the formation of a stop codon
35
What is a mis-sense mutation?
If the base change results in a code for a different amino acid
36
Define silent mutation.
If the base change still codes for the same amino acid as before
37
What is a deletion mutation?
If a nucleotide is lost from the DNA sequence, resulting in a ‘frame shift’ in translation
38
What is a mutagen?
A material or factor that increases the normal mutation rate, such as high energy radiation or chemicals
39
What is a chromosome mutation?
A change that occurs in a chromosome, often due to problems during meiosis
40
Define polyploidy.
The process of the genome doubling, resulting in organisms with multiple sets of chromosomes
41
What is non-disjunction?
The failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division
42
What is meiosis?
The type of nuclear division in which the number of chromosomes is halved
43
Define gamete.
Reproductive (sex) cell that fuses with another gamete during fertilisation
44
What does diploid mean?
Cell or nucleus containing pairs of homologous chromosomes (two sets of chromosomes)
45
What is haploid?
Cell or nucleus containing single, unpaired chromosomes (a single copy of each chromosome)
46
Define homologous chromosomes.
A pair of chromosomes, one maternal and one paternal, that have the same gene loci
47
What is crossing over?
The process whereby a chromatid breaks during meiosis and rejoins to the chromatid of its homologous chromosome, exchanging alleles
48
What are chiasmata?
Points at which paired chromosomes remain in contact during metaphase of meiosis, where crossing over occurs
49
Define recombination.
The rearrangement of genetic material, especially by crossing over in chromosomes
50
What is independent assortment?
The alleles of different genes get sorted into gametes independently of one another
51
Define independent segregation.
During the formation of gametes, each gamete receives just one gene copy, selected randomly
52
What is variation?
Differences between individuals, which can be interspecific or intraspecific
53
Define genetic diversity.
The greater the number of different alleles that all members of a species possess, the greater the genetic diversity of that species
54
What is allele frequency?
The number of times an allele occurs within the gene pool in a population, relative to all others at the same locus
55
Define gene pool.
All the different alleles of all the genes of all the individuals in a population at any one time
56
What is natural selection?
The process by which organisms better adapted to their environment survive, reproduce, and pass on advantageous alleles
57
What is directional selection?
Selection that favours one extreme of the range of characteristics, shifting the population curve
58
Define stabilising selection.
Selection that favours the mean of the distribution, increasing the frequency of the mean phenotype
59
What are polygenes?
Groups of genes responsible for controlling a characteristic
60
Define normal distribution curve.
A bell-shaped curve produced when a certain distribution is plotted on a graph
61
What is biodiversity?
The range and variety of genes, species, and habitats within a particular region
62
Define species.
A group of organisms that share a common ancestry and can breed together to produce fertile offspring
63
What is the binomial naming system?
Linnaeus’ system to name species, consisting of a generic name and a specific name
64
What is hierarchy in biological classification?
Groups within larger groups without overlap at each rank
65
Define artificial classification.
Classifying organisms based on differences useful at the time, such as colour or size
66
What is phylogenetic classification?
Classifying organisms based on evolutionary relationships between organisms and their ancestors
67
Define analogous characteristics.
Characteristics with the same function but different evolutionary origins
68
What are homologous characteristics?
Characteristics with similar evolutionary origins, regardless of their functions in the adult of a species
69
What is a taxon?
Each group within a phylogenetic biological classification
70
What is courtship behaviour?
A specialised behaviour that precedes the fertilisation of eggs to ensure successful reproduction
71
Define classification.
Organisation of living organisms into groups
72
What is taxonomy?
The practice of biological classification
73
What is a domain in biological classification?
Largest taxon, including bacteria, archaea, and eukarya
74
Define kingdom.
Second largest taxon in classification; Eukarya domain divides into Protoctista, Fungi, Plantae, and Animalia
75
What is a community?
The organisms of all species that live in the same area
76
Define population.
A group of organisms of the same species occupying a particular space at a particular time
77
What is species diversity?
Number of different species and number of individuals of each species within a community
78
Define ecosystem diversity.
Range of different habitats within a particular area
79
What is genetic diversity?
Variety of genes possessed by individuals that make up any one species
80
What is species richness?
The number of different species represented in an ecological community
81
What is the index of diversity?
A formula used to quantify the biodiversity of a habitat, considering the number of species and their abundance
82
Define biomass.
The total mass of living material, normally measured in a specific area over a given period of time
83
What is conservation?
Management of the Earth’s natural resources for maximum future use
84
What is intercropping?
The practice of growing two or more crops in close proximity to produce a greater yield
85
Define habitat.
The place where an organism normally lives
86
What is random sampling?
Sampling a population to eliminate bias, such as using grid squares
87
What is sampling bias?
When a sample is collected in a way that some members are more or less likely to be included than others
88
Define sample size.
The number of observations in a sample
89
What is the mean?
A type of average where you add up all the numbers and divide by how many numbers there are
90
What is the median?
A type of average found by ordering numbers and finding the middle number
91
Define mode.
A type of average that is the number occurring most often
92
What is standard deviation?
A measure of how spread out values are about the mean

biology key words (4 decks)

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