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As Biology (Year 1) > 4-Genetric Info, Variation, Relationships > Flashcards

4-Genetric Info, Variation, Relationships Flashcards

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1
Q

What are DNA molecules like in prokaryotic cells

A

Short, circular, not associated with proteins

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2
Q

Whats DNA like in eukaryotic cells

A

Long, linear, associated with proteins called histones
DNA molecule with a protein forms a chromosome

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3
Q

What is the DNA in chloroplasts and mitochondria of eukaryotes diffrent

A

Short, circular, not associated with proteins

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4
Q

What is a gene

A

A base sequence of DNA which codes for the amino acid sequence in a polypeptide or a functional RNA like rRNA

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5
Q

What’s a locus

A

A specific position a gene occupies on a DNA molecule

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6
Q

What’s a triplet and what does it do

A

A sequence of 3 DNA bases, codes for a specific amino acid

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7
Q

Why is the genetic code universal

A

A triplet can code for the same amino acids in all organisms

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8
Q

Why is the genetic code non overlapping

A

Each base in the sequence is read once
Eg 123,456 not 123,234,345,456

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9
Q

Why is the genetic code degenerate

A

An amino acid can be coded for by more than one triplet

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10
Q

What are exons and introns

A

Exons, Coding sequences for amino acids/rRNA/tRNA
Introns, non coding sequences
Exons are separated by introns

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11
Q

What’s a genome

A

Complete set of genes in a cell

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12
Q

What’s a proteome

A

Full range of proteins a cell is able to produce

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13
Q

What’s the structure of mRNA

A

Long, single helix
Contains uracil instead of thymine
Contains codons (3 bases complimentary to a DNA triplet)

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14
Q

What’s the structure of tRNA

A

Small, single stranded chain in a clover leaf shape one side is longer than the other (where amino acids attach)
Anticodon is complimentary to codons

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15
Q

What does transcription in prokaryotes result in

A

Direct production of mRNA from DNA

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16
Q

What does transcription in eukaryotes result in

A

Pre-mRNA which is spliced to form mRNA

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17
Q

What happens in transcription

A

Enzyme (DNA helicase) separate the two DNA stands exposing the nucleotide bases
Nucleotide bases on the template strand (one DNA stand) pair with complimentary nucleotides from the pool in the nucleus
RNA polymerase moves along the stand joining the complimentary nucleotides together forming pre-mRNA
When RNA polymerase reaches a terminator sequence it detaches and production of pre-mRNA finishes

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18
Q

During transcription how are eukaryotes spliced

A

DNA in eukaryotic cells have introns and exons, non coding introns would prevent the synthesis of a polypeptide
In pre-mRNA complimentary bases of the introns are removed leaving the exons to join together

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19
Q

What happens during translation

A

A ribosome attaches to a start codon on mRNA, a tRNA molecule with an anti codon pairs up with the codon on mRNA, tRNA carries a specific amino acid
The tRNA with a complimentary anticodon pairs with the next mRNA codon carrying another amino acid
Two amino acids on tRNA are joined by a peptide bond using an enzyme and ATP, process repeats
When the ribosome reaches a stop codon the ribosome, mRNA and tRNA molecules seperate

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20
Q

Whats a gene mutation

A

Change in the base sequence of chromosomes

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21
Q

What happens during a base substitution mutation

A

A base is swapped with a different base, if it causes the amino acid to change the bonds between them change, the protein formed and it’s shape changes so it can’t function properly
However DNA is degenerate so if a base is substituted and still forms the same amino acid no change occurs

22
Q

What happens during a base deletion mutation

A

A nucleotide is lost from the DNA sequence, all bases shift left changing all the triplet codes, different amino acid, different protein that can’t function

23
Q

What increases the rate of gene mutation

A

Mutagenic agents

24
Q

How can a mutation in the number of chromosomes during meiosis be caused

A

Spontaneously arise by chromosome non disjunction, chromosomes fail to seperate

25
Q

Process of meiosis

A

First division, homologous chromosomes pair with chromatids randomly (independent segregation), sections cross over, new combinations of maternal and paternal alleles, creates genetic variation
Second division, chromatids move apart, 4 cells formed

26
Q

Products of meiosis

A

Daughter cells genetically different from each other

27
Q

How does meiosis produce haploid cells from a single diploid cell

A

Chromosomes duplicated, two sets of divisions so each cell will contains one set of chromosomes and thus are haploid

28
Q

How to calculate the number combinations of chromosomes in each daughter cell

A

2^n
n is the number of homologous pairs

29
Q

Meiosis vs mitosis

A

Meiosis
2 nuclear divisions, produces haploid cells, introduces genetic variation
Mitosis
1 nuclear division, produces diploid cells, produces genetically identical cells

30
Q

How do identify meiosis in a lifecycle

A

Where a diploid cell (2n) become a haploid cell (n)

31
Q

How is genetic variation increased further in humans

A

Random gametes fuse therefore the number of combinations is (2^n)^2

32
Q

What’s genetic diversity

A

A factor (the number of different alleles of genes in a population) enabling natural selection to occur

33
Q

Principals of natural selection causing populations to evolve

A

Random mutation results in new alleles of a gene
Many mutations are harmful but can also benefit increasing reproductive success
Advantageous allele inherited by offspring
Over generations allele increases in frequency in population

34
Q

What adaptations may occur due to natural selection

A

Anatomical (structure), longer beak
Physiological (chemical reactions), special enzymes
Behavioural, survival instincts

35
Q

What’s directional selection

A

A specific extreme trait has a selective advantage due to a change in environment
eg antibiotic resistance, as antibiotics are used more (change in environment) bacteria with allele for resistance to antibiotics thrive and reproduce passing on allele

36
Q

What’s stabilising selection

A

The modal trait remains the same as environment stays the same, causes extreme traits to be lost
eg human birth weight, having a healthy weight provides best chances of survival, pass on allele to offspring

37
Q

How to know if two organisms are pet of the same species

A

Able to produce fertile offspring

38
Q

Whats courtship behaviour

A

A necessary precursor for successful mating

39
Q

How does courtship allow for species recognition

A

Recognition of members from their own species, ensure mating only occurs between members of the same species, produce fertile offspring
Identify a male capable of breeding, partners need to be sexually mature fertile and receptive to mating
Forming a pair bond, successful mating and raising of offspring
Synchronise mating, occurs when the best chance of the egg meeting the sperm is
Ability to breed, member of opposite sex brought into a physiological state allowing for breeding

40
Q

What’s a phylogenetic classification system

A

Arranges species into groups based on their evolutionary origins, relationships
Use of a hierarchy, smaller groups placed into larger groups, no overlap between groups
Each group is a taxon

41
Q

What hierarchy do the taxa represent

A

Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species

42
Q

How is each species universally identified

A

By a binomial
Name of genus (capital letter) species (lowercase)

43
Q

How are evolutionary relationships between organisms clarified nowadays

A

Immunology and genome sequencing has advanced

44
Q

What’s biodiversity

A

A range of habitats, can be small and local or earth

45
Q

What’s the richness of species

A

Measure of the number of different species in a community

46
Q

What’s an index of diversity and the equation

A

Relationship between number of species in a community and number of individuals in each species

d= N(N-1)/sum of n(n-1)
N= number of organisms of all species
n= number of organisms of each species
Higher value, higher species diversity

47
Q

Which farming techniques reduce biodiversity, how to balance this with farming

A

Removal of hedgerows, plant hedgerows rather than erect fences as field boundaries

Creating monocultures, create natural meadows and use hay for silage

Filling in ponds, maintain ponds and create new ones

Overgrazing of land, leave cutting of verges until after flowering when seeds have dispersed

48
Q

How can you investigate diversity by comparing observable characteristics and disadvantages

A

Observable characteristics are determined by genes and environmental influences. The variety of characteristics depends on the number of alleles of the gene

Characteristics are polygenic and altered by environment, inferring DNA differences from observable characteristics has been replaced with observing DNA itself

49
Q

How can you compare genetic diversity by base sequence of DNA

A

Base sequence of DNA can be read and compared to that of another organism, similar DNA base sequence shows similar features between organisms showing a close evolutionary relationship, due to mutations a new species will have a different DNA base sequence

50
Q

How can diversity be investigated by comparing the base sequence of mRNA

A

Base sequence on mRNA is complimentary to DNA, genetic diversity can be measured by comparing DNA between organisms and thus mRNA

51
Q

How can diversity be investigated by comparing the amino acid sequence of proteins encoded by DNA/mRNA

A

Amino acid sequence is determined by mRNA which is determined by DNA, similarity between amino acid sequences of two different organisms can show genetic relation

As Biology (Year 1) (5 decks)

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