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Genetic information, variation and relationships between organisms Flashcards

1
Q

compare the DNA in Eukaryotic cells with DNA in Prokaryotic cells

A

+Neucleotide structure is the same as deoxyribose attached to phosphate and a base
+Adjacent nucleotides joined by phosphodiester bonds
+DNA in mitochondria and chloroplast have a similar structure to DNA in prokaryotes

-Eukaryotic DNA is longer
-Eukaryotic DNA is linear whereas DNA is circular
-Eukaryotic DNA is associated with histone proteins whereas Prokaryotic DNA is not

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2
Q

what is a chromosome?

A

A chromosome is a long, linear DNA and is associated with histone proteins, and is located in the nucleus of Eukaryotic cells

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3
Q

what is a gene?

A

A sequence of DNA bases that code for amino acids of a polypeptide and functional RNA

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4
Q

what does Triplet code mean?

A

A sequence of 3 DNA bases called a Triplet which code for specific amino acids

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5
Q

what does the term Universal mean in relation to genetic code?

A

The same base triplets code for the same amino acids in all organisms

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6
Q

what does Non-overlapping mean?

A

Each base is part of only one Triplet so each Triplet is read as a discrete unit

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7
Q

what does degenerate mean?

A

An amino acid can be coded for by more than one base Triplet

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8
Q

what are non-coding base sequences and where are they found?

A

non-coding base sequences are DNA that does not code for amino acid sequence and are found between genes and within genes (introns)

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9
Q

what are introns?

A

Base sequence of a gene that does not code for amino acids in Eukaryotic cells

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10
Q

what are exons?

A

Base sequence of a gene coding for amino acid sequence in a polypeptide

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11
Q

Define genome

A

The complete set of genes in a cell

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12
Q

define proteome

A

the full range of proteins that a cell can produce

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13
Q

what is transcription

A

Production of mRNA from DNA, in the nucleus

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14
Q

what is translation?

A

Production of polypeptide from the sequence of codons carried by mRNA, at ribosomes

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15
Q

compare and contrast the structure of mRNA and tRNA

A

+Both a ginger polynucleotide strand
-tRNA is folded into a clover shape whereas mRNA is linear
-tRNA has hydrogen bonds between paired bases and mRNA doesn’t
-tRNA is shorter whereas mRNA is longer
-tRNA has an anticodon and mRNA has codons

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16
Q

Describe how mRNA is formed by transcription in Eukaryotic cells

A

1-hydrogen bonds between DNA bases break
2-only one DNA strand acts as a temple
3-Free RNA nucleotides align next to their complimentary bases on the template strand
4-RNA polymerase joins adjacent RNA nucleotides
5-forms phosphodiester bonds via a condensation reaction
6-pre-mRNA is formed and is spliced to remove introns forming mRNA

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17
Q

describe how production of mRNA in Eukaryotic cells in different from production of mRNA in prokaryotes

A

-pre-mRNA produced in Eukaryotes whereas mRNA is produced directly in Prokaryotic cells because genes in prokaryotic cells don’t contain introns so there s no splicing

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18
Q

describe how translation leads to the production of a polypeptide

A

1-mRNA attaches to a ribosome and the ribosome moves to a start codon
2-tRNA brings specific amino acids
3-tRNA anticodons bind to complimentary mRNA codon
4-ribosomes move along to the next codon
5-tRNA released after amino acid joined polypeptide
6-ribosomes move along mRNA to form the polypeptide until a stop codon is reached

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19
Q

what is the role of ATP in translation

A

hydrolysis of ATP to ADP +Pi releases energy so amino acids joined to tRNAs and peptide bonds form between amino acids

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20
Q

describe the role of tRNA in translation

A

attaches and transports a specific amino acid and the tRNA anticodon complimentary base pairs to mRNA codon forming hydrogen bonds. 2 tRNAs bring amino acids together so peptide bonds can form

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21
Q

describe the role of ribosomes in translation

A

mRNA binds to ribosome with space for 2 codons allowing tRNA with anticodons to bind. This catalyses the formation of peptide bond between amino acids

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22
Q

what is a gene mutation?

A

a change in the base sequence of DNA (deletion and substitution)

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23
Q

what is a mutagenic agent?

A

a factor that increases rate of gene mutation

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24
Q

explain how a mutation can lead to the production of a non-functional protein or enzyme

A

1, changes sequence of base Triplet in DNA so the sequence of codons is changed on mRNA, so the sequence of amino acids in polypeptide is changed and bonds (hydrogen, ionic and disulfide bridges) are changed. so the tertiary structure is changed of a protein and enzymes active site changes shape so no ESC can form

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25
explain the possible effects of a substitution mutation
Base in DNA is replaced by a different base changing one Triplet so the mRNA codon is changed, so one amino acid changes in the polypeptide
26
explain the possible effects of a deletion mutation
one base is removed from DNA sequence which changes the sequence of DNA Triplet therefore changing the sequence of mRNA codons, and changing the amino acid sequence in the primary structure of polypeptide - bonds change (hydrogen, ionic and disulfide) changing tertiary structure
27
describe features of homologous chromosomes
they have the same length, same genes at the same loci, but may have different alleles
28
what is a diploid
has 2 complete sets of chromosomes
29
what is a haploid
has a single set of unpaired chromosomes
30
describe how a cell divides by meiosis
1- meosis 1 the homologous chromosomes separate and chromosomes arange into homologous pairs. Crossing over between homologous chromosomes occurs - independent segregation of homologous chromosomes 2-meosis 2 separates the chromatids
31
what is the outcome of meosis?
4 genetically varied daughter cells and are normally haploid
32
explain why the number of chromosomes is halfed during meosis
homologous chromosomes are separated during meosis 1
33
explain how crossing over creates genetic variation
-homologous pairs of chromosomes associate from a bivalent -chiasmata form -alleles are exchanged between chromosomes creating a new combination of alleles on chromosomes
34
explain how independent segregation creates genetic variation
-homologous pairs randomly align at the equator creating a different combinations of maternal and paternal chromosomes
35
how is genetic variation increased?
-mutations -meosis -random fertilisation -creating new allele combinations
36
explain the importance of meosis
two devision creates a haploid gamete so diploid number is restored at fertilisation
37
explain the different outcomes of mitosis and meosis
*mitosis produces 2 daughter cells whereas meosis produces 4 *mitosis maintains the chromosome number whereas meosis halves the chromosome number *mitosis produces genetically identical daughter cells whereas meosis produces genetically varied daughter cells
38
describe how mutations in the number of chromosomes arise
*spontaneously by chromosome non-dusjunction during meosis
39
what is genetic diversity?
the total number of genetic characteristics in the genetic make up of a species.
40
what are alleles and how do they arise?
variations of a particular gene with a difference DNA base sequence which arise by mutation
41
what is a population?
a group of interbreeding individuals of the same species
42
explain the importance of genetic diversity
-enables natural selection to occur -New allele may benefit possessor giving a selective advantage (increased chances of survival)
43
what is evolution?
change in allele frequency over many generations in a population occurring through the process of natural selection
44
exain the principles of natural selection in the evolution of populations
mutations produce new alleles of a gene, organisms would have a selective advantage and are more likely to survive and have an increased reproductive success. These advantageous allele is inherited by members of the next generations (offspring) and over generations alleles increase in frequency in the population
45
describe the 3 types of adaptions
Anatomical- physical features which increase chance of survival Physiological- chemical reactions that increase chance of survival Behavioural- ways in which an organism acts that increase chance of survival
46
what is directional selection?
environmental conditions change and the phenotypes best suited for the conditions are more likely to survive.
47
what is stabilising selection?
successful characteristics are perserved and those of greater diversity are reduced, does not occur due to changes to the environment
48
What is the significance of genetic diversity?
Varitation is nessisary for adaption and survival. -large polpulations have a greater allele diversity
49
What is the equasion for Allele frequence?
the number of a species type of allele/ the total number of alleles in the gene pool
50
Describe darwins theory of evolution?
individual with better adaptions to their enviroment compete better than others, to survive longer and reproduce more and so pass on their succsessful genes to the next generation
51
What is a gene pool?
within a population of a species their s a wide variety of alleles
52
What is disruptive (diverging) selection?
When both extremities of phenotypes are selected over intermediate types
53
what is a species?
a group of organisms that can produce fertile offspring
54
suggest why 2 different species are unable to produce fertile offspring
-different species have different chromosome numbers so offspring may have odd chromosome number and so homologous pairs cannot be formed therefore meiosis cannot occur to produce gametes
55
why is courtship behaviour a necessary precursor to successful mating?
-allows recognition of same species members so leading to fertile offspring being produced -allows for attraction of opposite sex -to establish a pair bond to raise young
56
describe a phylogenetic classification system
species are arranged into groups called a taxa based on their evolutionary origins and relationships using a hierarchy (smaller groups are placed within larger groups, no overlapping between groups)
57
Name the order of the hierarchy of classification
Domain Kingdom phylum class order family genus species
58
how is each species universally identified?
a binomial consisting of the name of its genus and species
59
suggest an advantage of binomial naming
it is universal so there is no confusion as many organisms have more than one common name
60
describe 2 advantages that have helped to clarify evolutionionary relationships between organisms
1, advances in genome sequencing which allows comparison of DNA base sequences, can see how mutations build up over time 2, advances in immunology which allows comparison of protein tertiary structure
61
describe 2 advantages that have helped to clarify evolutionionary relationships between organisms
1, advances in genome sequencing which allows comparison of DNA base sequences, can see how mutations build up over time 2, advances in immunology which allows comparison of protein tertiary structure
62
Why is classification important?
Allows us to identify the similarities and differences between organisms, and the evolutionary history of an organism -gives an universal name for easy study
63
what is the binomial system?
A unique universal name in Latin; Homo sapiens
64
What is natural classification
-organisms are grouped together based on homologous structures -shared evolutionary origin
65
What is artificial classification?
-should not be based on analogous structures -similar functions but do not have a common origin (wings on birds and bats)
66
what is taxonomy?
The study of groups within a natural classification
67
What is taxonomic ranking?
-Hierarchical, so large groups are subdivided into smaller groups -Allows larger groups to be differentiated from larger groups -no over lapping
68
What does a phylogenetic classification system show
The evolutionary links between each taxonomic group with respect to time (phylogenetic tree)
69
What is the classification order?
Domain-Kingdom-Phylum-Class-Order-Family-Genus-Species
70
What is courtship behaviour?
Is a pattern of behaviour used to attract a mate
71
Define species recognition.
Only members of the same species mate, resulting in fertile offspring
72
Define pair bond formation.
For successful mating, male and female of the same species recognise each other as individuals and act in a coordinated way. -assist in the raising of offspring
73
What is synchronisation of breeding behaviour?
-females only ovulate at certain times, signals indicate that she is entering oestrus and often males will signal specific behaviour to entice the females to mate, and then the female will signal that she is receptive- successful recognition increases chances of fertilisation.
74
What are the types of courtship behaviour?
.Territorial behaviour- the male defends a territory which contains fertaile females .Construction of nests .Courtship dances .Vocalisation .Pheromones
75
What are the three plant genomes for plant classification
-mitochondrial -nuclear -choroplast
76
How do we make immunological comparisons?
Albumins and antibodies are both proteins -antibodies of one species will react when exposed to blood serum, containing the proteins, of another - a range of antibodies will be created that respond to the antigenic binding sites on the albumin -albumin from one of the species being investigated is injected into another outroup species -antibodies respond against albumin are collected -then exposed to the blood proteins of each of the other species species more closely related to the outgroup will exhibit a weaker reaction
77
what is a biodiversity?
a variety of living organisms relating to a range of habitats
78
what is a community?
all populations of different species that live in an area
79
what is species richness?
a measure of the number of different species in a community
80
what does index of diversity do
describes the relationship between: the number of species in a community (species richness) and the number of individuals in each species (population size)
81
suggest why index of diversity is more useful than species richness
-takes into account number of individuals in each species so takes into account that some species may be present in small or high numbers
82
describe how index of diversity values can be interpreted
high- many species present evenly represented low-habitat dominated by one or a few species
83
how can genetic diversity between or within a specified be measured?
-compare frequency of measurable or observable characteristics -compare base sequence of DNA -compare base sequence of mRNA -comoare amino acid sequence of a specific protein encoded by DNA and mRNA
84
Explain how comparing DNA,mRNA, and amino acid sequence can indicate relationships between organisms within a species and between species
more differences in sequence suggest more distantly related a species is as mutations build up over time and so there are more changes in the DNA base sequence, and more mutations cause more changes in the amino acid sequence
85
Explain the change in methods of investigating genetic diversity over time
early estimates are made by inferring DNA differences from measurable or observable characteristics however many are influenced by the environment and many are coded for by more than one gene Now gene technologies allow this to be replaced by direct investigation of DNA sequences
86
Explain the key considerations in quantitative investigations of variation within a species.
-Collect data from a random sampling which removes bias -Large smaple size so is representative -Ethical sampling -Calculate the mean value of collected data and the standard deviation of that mean -Use statistical test, analyse whether there is a significant difference between populations

Biology (8 decks)

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