4 - DNA, RNA And Classification / Variation Flashcards
1
Q
What are the 4 bases
A
Adenine
Thymine
Guanine
Cytosine
2
Q
What are histones
A
Proteins that DNA get wound around
3
Q
What charge is DNA
A
Slightly negative
4
Q
What charge are histones
A
Slightly positive
5
Q
What is the combination of DNA and histones called
A
Nucleosome
6
Q
What is gene expression
A
Characteristic functional in a phenotype
7
Q
DNA is wrapped + coiled around histone proteins to form a substance called what?
A
Chromatin
8
Q
Do prokaryotes have histones
A
No
9
Q
Why do prokaryotes not have histones
A
More simple
Usually smaller genomes as Si plaid functions
10
Q
How does DNA exist in prokaryotes
A
DNA is circular, free in cytoplasm in 2 forms
- circular chromosomes
- small amounts in circular plasmids
11
Q
Are mitrochondria and chloroplasts found in both prokaryotes and eukaryotes
A
No
Only eukaryotes as memebrane bound
12
Q
Do mitochondria and chloroplasts have their own DNA
A
Yes
13
Q
Eukaryotic cells contain …………. DNA that exist as ………….
A
Linear
Chromosomes
14
Q
Where are chromosomes found in a eukaryotic cell
A
Nucleus
15
Q
What has to happen to DNA so that it can fit into the nucleus and why
A
It’s very long so wound up
16
Q
Are histones protines?
A
Yes
17
Q
What do histone proteins do
A
Support the DNA
18
Q
Do prokaryotes carry DNA in chromosomes
A
Yes
19
Q
Describe the DNA molecules in prokaryotes
A
Shorter
Circular
Isn’t wound around histones
20
Q
How does DNA in prokaryotes fit into cells
A
Supercoiling
21
Q
What is a gene
A
A sequence of DNA bases that codes for either a polypeptide or functional RNA
22
Q
The sequence of amino acids in a polypeptide forms the ………….. of a protein
A
Primary protein
23
Q
What determines the order of amino acids in a particular polypeptide
A
The order of bases in a gene
24
Q
What is each amino acid coded for by
A
three bases in a gene called a triplet
25
What is the first stage of protein synthesis
DNA is first copied to messenger RNA
26
Genes that don’t code for a polypeptide code fro what
functional RNA
27
What is functional RNA
RNA molecules other than mRNA, which preform special tasks during protein synthesis, and ribosomal RNA, which forms part of ribosomes
28
What is a called genome
The complete set of genes in the cell.
29
What is a cells proteome
The full range of proteins that the cell is able to produce
30
What are introns
In eukaryotic DNA, genes that do code for polypeptides contain sections that don’t code for amino acid , called introns
31
Can there be several introns within a gene
Yes
32
What are exons
Bits of a gene that do code for amino acids
33
Introns are ……… durning protien synthesis and why
Removed
So they don’t affect the amino acid order
34
Does prokaryotic DNA have introns
No
35
Eukaryotic DNA also contains regions of multiple repeats outside of genes, what does this mean
These are DNA sequences that repeat over and over
36
In eukaryotic DNA do multiple repeated outside of genes code for amino acids, so what are they called
No
Non coding repeats
37
What is an allele
A form of a gene
38
Why does each allele have slightly differnt versions of the same polypeptide
The order of bases is slightly differnt
39
How many pairs of chromosomes do humans have
23 pairs
40
What are pairs of matching chromosomes called
Homologous pairs
41
Describe homologous pairs
Both chromosomes are the same size and have the same genes, although the pay could have differnt alleles.
Alleles coding fro the same characteristics will be found at the same fixed position (locus) on each chromosome in anhomologous pair
42
Centre of a chromosome name
Centromere
43
What is an allele
Version of a gene
44
What is a gene
Section of DNA that codes for a particular characteristics
45
What is loci
Location of the gene in a chromosome
46
What is a chromosome
DNA in nucleus of eukaryotic cells is linear and arranged in chromosomes
47
What is chromatin
DNA wrapped and coiled around histone proteins
48
What does DNA stand for
Deoxyribose nucleic acid
49
What is a polypeptide
Chain of amino acid connected by peptide bonds
50
in prokaryotes, DNA isn’t wound around histones so how does it fit in the cell
Condenses by supercoiling
51
What is a codon
Sequence of 3 DNA / RNA nucleotides that correspond with a specific amino acid
52
What are exons
Code for an amino acid
53
What are introns
Don’t code of amino acids
(Removed during protein synthesis )
54
Does prokaryotes have both exons and introns
only exons
55
What. Happens first transcription or translation
Transcription
56
Where does transcription happen
In the nucleus
57
Where does translation happen
In the cytoplasm by the ribosome
58
What is splicing
Process of cutting out introns
Leaving on exons
59
What does a mRNA triplet code match to
A specific amino acid
60
What is a codon
mRNA strand being read in triplets
61
Where is an anticodon found
On tRNA
62
Explain transcription
The hydrogen bonds in the DNA, between complementary base pairs, is broken by an enzyme.
• two exposed strands, one used as a template.
2. One of the DNA strands is used as a template to make the mRNA molecule, the template is called the antisense strand.
3. Free nucleotides line up by complementary base pairing and adjacent nucleotides are joined by phosphodiester bonds thus forming a molecule of mRNA.
• The enzyme RNA polymerase catalyses the formation of phosphodiester bonds.
4. When a stop codon is reached this ceases. As the RNA polymerase moves away the DNA rejoins, with only 12 bases being exposed at a time to reduce the chance of damage to the DNA.
5. In eukaryotic cells the pre-mRNA is then spliced to remove the introns leaving just a strand of exons.
6. The mRNA then moves out of the nucleus through a pore and attaches to a ribosome in the cytoplasm which is the site of next stage of protein synthesis called translation.
63
What is broken in DNA during transcription to expose the 2 strands
Hydrogen bonds between complementary base pairs.
64
What is the template strand in transcription called
Antisense strand
65
How do adjacent nucleotides join up and for a mRNA molecule
And what is the catalyst
Phosphodiester bonds
Enzyme RNA polymerase catalysed
66
When does the RNA polymerase move away and the DNA rejoins in transcription
When a stop codon is reached
67
How many bases on DNA are exposed at one time in transcription
And why
12
To reduce chance of damage to DNA
68
What happens to pre-mRNA to produce mRNA
Splicing to remove introns
69
How does mRNA exit the nucleus
And where does it go
Through a nuclear pore
and attached to a ribosome in the cytoplasm
70
Why is DNA kept in the nucleus during protien synthesis
It’s more prone to damage ( mutations) outside the nucleus
71
Describe translation
1. mRNA attaches to a ribosome
2. transfer RNA collects amino acids from the cytoplasm and carries them to the ribosome.
• can only carry one type of amino acid, and a triplet of bases (anticodon) at the other.
3. tRNA attaches itself to mRNA by complementary base pairing
• two molecules attach to mRNA at a time.
4. The amino acids attached to two tRNA molecules join by a peptide bond and then tRNA molecules detach themselves from the amino acids, leaving them behind.
5. This process is repeated thus leading to the formation of a polypeptide chain until a stop codon is reached on mRNA
• this ends the process of protein synthesis.
A ribosome can join up to 15 amino acids per second until the stop codon is reached. Furthermore up to 50 ribosomes can move along the same strand of mRNA behind one another so that several proteins can be assembled simultaneously.
72
What is the simplifed definition of translation
Amino acids join together to form a polypeptide chain
73
How many tRNA molecules can attach to mRNA at one time
2
74
What is the bond between 2 amino acids
Peptide bond
75
Is tRNA single or double stranded
Single
76
Describe the length of
DNA, mRNA and tRNA
DNA - long
mRNA- variable
tRNA- short
77
What shape is mRNA
Single helix / strand
78
What is the shape of tRNA
Clover
79
What type of sugar is in DNA
Deoxyribose
80
What type of sugar is in mRNA
Ribose
81
What type is sugar is in tRNA
Ribose
82
What bases are in DNA
Adenine (check )
Thymine
Cytosine
Guanine
83
What bases are in mRNA and tRNA
Adenine
Uracil
Cytosine
Guanine
84
Is DNAs quantity Large or small and is it constant
Large and constant
85
is mRNA quantity large or small and is it constant
Smaller
Varies
86
is tRNA quantity large or small and is it constant
Smaller
Varies
87
What is the stability in
DNA, mRNA and tRNA
DNA - stable
mRNA - unstable
tRNA - relatively stable.
88
How many possible triplets are there
And how many AA are there
64
20 AA
89
What are the features of the genetic code
non-overlapping: meaning that each triplet is only read once and triplets don’t share any bases.
• Genes are separated by non-coding repeats of bases.
• is degenerate: meaning that more than one triplet codes for the same amino acid,
90
What does genetic code being degenerate reduce
Mutations
91
homologous pairs consist of ……. Chromosomes that carry the same gene
But they arnt identical, why?
2
They can carry differnt alleles of the same gene
92
What sex chromosomes do females have
2 X chromosomes
93
What sex chromosomes do males have
X and Y chromosome
94
What does homologous pair of chromosomes contain
Contain the same set of genes
95
What 3 groups are in an amino acids
Carboxylic acid
Amino group
r group changes
96
What is required to form the bond between amino acids and tRNA molecule to from
And where else is thus required in translation
ATP
To join 2 amino acids together
97
What is the genetic code
The sequence of base triplets (codons) in mRNA which codes for specific amino acids
98
What does it mean that the genetic code is universal
The same specific base triplets code for the same amino acid in all living things
99
What are gametes
The sperm and eggs cells
They join togetehr during fertilisation to from a zygote
Which divides and develops into a new organism
100
How many chromosomes do normal body cells have (in humans)
What is the term to describe thus
46
Diploid
101
How many chromosomes are in the gametes in humans
And what is the term to describe this
23
Haploid
102
T or f
Fertilisation is random
T
103
What does random fertilisation produce
Zygotes with differnt combinations of chromosomes to both parents
104
What increases genetic diversity within species
The mixing of genetic material in sexual reproduction
105
Where does meiosis happen
In reproductive organs
106
What happens before meiosis starts
The DNA unraveled and replicates so there are two copies of each chromosomes called chromatids
The DNA then condensed to from double armed chromosmes, each made form 2 sister chromatids. The sister chromatids are joined in the middle by a centromere
107
How are 2 sister chromatids joined
By a centromere
108
Describe meiosis 1
The chronometer arrange themselves into homologous pairs
These homologous pairs are then separated halving the chromosome number
109
Describe meiosis 2
The pairs of sister chromatids that make up each chromosome are separated (the centromere is divided)
110
What is the product of meiosis
4 haploid cells that are genetically differnt from each other are produced
111
What can happen to chromatids in meiosis 1
homologous pairs of chromosomes come togetehr and pair up
The chromatids twist around each other and bits of the chromatids swap over
The chromatids still contain the same genes but now have a differnt combination of alleles
112
What 2 main events happen during meiosis that lead to genetic variation
1) crossing over of chromatids
2) independent segregation of chromosomes
113
How does crossing over of chromatids lead to genetic variation
Each of the four daughter cells formed form meiosis contain chromatids with differnt alleles
114
How independent segregation of chromosomes leaded to genetic variation
Each homologous pair of chromosomes in your cells is made up of one chromosome for, your mum (maternal) and one form your dad ( paternal )
When the homologous pairs are separated in meiosis, it’s completly random which chromosome form each pair ends up in which daughter cell
So the 4 daughter cells produced by meiosis have completely differnt combinations of those paternal and maternal chromosomes
This shuffling of the chronometer leads to genetic variation of any potential offspring
115
Outcomes of mitosis
Produced cells with the same number of chromosomes as the parent cell
Daughter cells are genetically identical to each other and to the parent
2 daughter cells
116
Outcomes of meiosis
Produced cells with half the number of chronometer as the parents cell
Daughter cells are genetically differnt form one another and the parent cells
Produced 4 daughter cells
117
My do mitosis and meiosis have differnt outcomes
Mitosis only involves one division which separates the sister chromatids, whereas meiosis has two divisions, which separate the homologous pairs, and then the sister chromatids. There’s no pairing or separating of homologous chromosomes in mitosis, and so no crossing over ot independent segregation of chromosomes.
118
In humans
How many chromosomes do the daughter cells have after meiosis
23
119
What is it called when something goes wrong in meiosis and the cell produced contains a variation in the number of whole chromosomes or parts of chromosomes
Chromosome mutation
Caused by errors during meiosis
120
What does chromosome mutations lead to
Inherited conditions because the errors are Present in the gametes
121
What is non disjunction
Failure of the chromates to separate properly
122
What does non-disjunction of chromosomes 21 during meiosis lead to
Down syndrome
123
What is Down syndrome caused by
A person having an extra copy of chromosome 21
Non disjunction means that chromosome 21 fails to seperate properly during meiosis so one cell gets an extra copy of 21 and another gets none
When the gamete with the extra copy fuses to another gamete at fertilisation, the resulting zygote will have 3 copies of chromosomes 21
124
What do gene mutations involve
A Changw in the DNA base sequence of chromosomes
125
What two types of gene mutations are there
Substitution
Deletion
126
What is substitution mutation
One bass is substituted with another
127
What is a deletion mutation
One base is deleted
128
What does a mutation in a gene chase
order of DNA bases Change
So amino acid changes
So the sequnce if amino acid changes
So the protein coded for could be altered
129
Why do not all mutations affect the offer of amino acids
The degenerate nature of the genetic code means that some amino acids are coded for by more than one DNA triplet
This means that not all substitutions will result in a change to the amino acid sequence of the protein
some substitution will still change for the same amino acid
130
Will substitution mutation always leads to changed in the amino acid sequence
No
131
Will deletion mutation always leads to changed in the amino acid sequence
Yes
132
how does deletions affect amino acids sequence
It will change the number of bases present
Which will cause a shift in all the vase triplets after it
133
T or f
Mutations occur spontaneously
T
134
somethings cause an increase in rate of mutations
are called what
Mutagenic agents
135
Give some examples of mutagenic agents
Ultraviolet radiation
Ionising radiation
Some chemicals and some viruses
136
What are the phases of meiosis
Interphase
Prophase
Megaphone
anaphase
Telophase
Prophase 11
Metaphase 11
Anaphase 11
Telophase 11
Cytokinesis 11
137
What is the DNA like in interphase
Already 2x the amount
DNA in nucleolus as chromatin
(The nucelar envelope is intact)
138
describe the dna in prophase
DNA in chromosomes
The sisterchromasomes joined at the centromere
139
When does the nucelar envelope break down in meiosis
Prophase
140
In prophase 1
Meiotic spindles form long proteins called ……
Microtubules
141
What happens in metaphase 1 in meiosis
Pairs of chromosomes line up on equator on spindle fibres
142
What phase can independent assortment only happen in in meiosis
Metaphase 1
143
What 3 things in meiosis can lead to genetic variation
Independent assortment
Random fertilisation
Crossing over
144
What does crossing over mean ( meiosis )
Can have section of DNA exchange when they overlap
145
The closer the gene is to the chromosome the ………
It is to be exchanged in crossing over
Less likeY
146
Describe anaphase 1 meiosis
Homologous pairs separate + are pulled to centriole by spindle fibres attached to centromeres
147
Describe telophase in meiosis
Chromomes reach poles
148
Describe cytokinesis meiosis
Nuclear membrane reforms
Chromosomes —> chromatin
149
Descirbe prophase 2 meiosis
The chromosomes condense and become visible again
The nuclear envelope breaks down
Spindle fibres begin to develop
150
Describe metaphase 2 meiosis
Chromosomes line up at equator
Spindle fibres attach to centromere - breaking centromere
151
Describe anaphase 2 meiosis
Sister chromatids are pulled to opposite ends of the cells be spindle fibres
152
How does structure of DNA relate to its function
• The sugar-phosphate backbone/double stranded so protects the bases and therefore maintains the genetic code
• Long molecule so can store a lot of information
• Base sequence so allows coding for amino acid sequence in a polypeptide
• Double stranded so each strand acts as a template so allows accurate replication
• Many hydrogen bonds so keeps double strands stable
• Hydrogen bonds are weak so allows unzipping of the strands during replication
• Complimentary base pairing so allows accurate replication
• Coiled so it is compact so a lot of information can be stored
153
What is a gene mutation
Change in the base sequence of chromosomes
154
what 2 ways can gene mutation happen during dna replication
Base deletion
Base substitution
155
What do not all base subsititutions cause a change in sequence of encoded amino acids
Due to the degenerate nature of the genetic code
156
What are mutagenic agents
Increase rate of gene mutation
157
What is essential for evolution to take place by natural selection
Variation
158
Without natural selection what can’t happen
Species can’t evolve and survive changing conditions
159
What can a mutated cell developer into
A tumour
160
Only what can mutations result in
New alleles
161
Meiosis and random fertilisation does not result in……….. but does result in…..
New alleles
NEW COMBINATIONS of ALLELES
162
What is a substitution mutation
one base takes the place of another
163
What is a deletion mutation
where one base is removed
164
in a deletion mutation,
Because the sequence changes completly after the mutation it is referred to as what
Frameshift
165
the earlier a deletion mutation happens the …….. effect it has
Bigger
166
What is chromosomes non-disjunction
+ examples of where life is possible
sometimes something goes wrong during gamete formation and a gamete will have two of one type of chromosome not one. This means that if it is fertilised by a normal gamete the resulting embryo will have cells with three of one type of chromosome (this is called trisomy).
In humans this would usually make the embryo non-viable, however there are conditions where life is possible -
Three of chromosome number 21 – known as Down's syndrome
Three of chromosome number 18 – known as Edward's syndrome
Three of the sex chromosomes – XXY – known as Klinefelter's syndrome
Or XYY Jacob's syndrome
167
Do formation of bivalent and chiasmata happen in mitosis or meiosis
Meiosis
168
Does separation of chromatids happen in mitosis and meiosis
Both
169
Fern reproduction lifecycle
In this life-cycle (the fern) meiosis results in the formation of spores not of gametes. The spores divide by mitosis to become what is called a gametophyte. The eggs and sperm are produced by mitosis and fuse to form a diploid zygote.
170
What is disjunction
Disjunction is the normal separation or moving apart of chromosomes toward opposite poles of the cell during cell division
171
What is non disjunction
Nondisjunction means that a pair of homologous chromosomes has failed to separate or segregate at anaphase so that both chromosomes of the pair pass to the same daughter cell.
172
Advantages of sexual reproduction
Variation so can adapt for survival to changing conditions
Happens over many gernation ( the offspring are more adapted than the parents)
173
Disadvantages of sexual reproduction
Slower (need a mate)
Courtship behaviour
Raid young
174
Advantages of asexual reproduction
Clones - many if favourable conditions
Quick as no mate (energy efficient)
175
Disadvantages of asexual reproduction
Less genetic variation so less resistant to disease
More vulnerable to changing conditions
Completion for same resorses
Slower rate of evolution
176
What is the genetic diversity
The number of differnt alleles of genes in a species or population
177
What is genetic diversity within a population increased by
Mutations in the dna - forming new alleles
Differnt alleles being introduced into a population when individuals form another population migrate into them and reproduce. This is known as gene flow
178
What does genetic diversity allow
Natural selection
179
What is a population
A group of organisms of one species living in a particular habitat
180
What is genetic bottleneck
An event that causes a big reduction in a population
181
How does a genetic bottleneck neck reduce genetic diversity
A big reduction in population
This reduces the number of differnt alleles in the gene pool and so reduces genetic diversity
The survivors reproduce and a larger population is created from a few individuals
182
What is a gene pool
The complete range of alleles in a population
183
Name a type of genetic bottleneck neck
Founder effect
184
What is the founder effect
Describes what happens when a few organisms from a population start a new colony and there are only a small number of differnt alleles in the inital gene pool
The frequency of each alleles in the new colony might be very differnt to the frequency of those alleles in the origional population
Thus may lead to a higher incidence of genetic disease
185
Give an example of why founder effect might occur
Migration leading to geographical separation or if a new colony is separated form the origional population
186
What does natural selection do
Increase advantageous alleles in a population
187
What are the 3 types of adaptations
Behavioural
Physiological
Anatomical
188
What is a behavioural adaptation
Ways an organism acts that increase its chance of survival and reproduction
189
What is a physiological adaptation
process inside an organisms body that increases its chance of survival
190
What is an anatomical adaptation
Structual fractures of an organismsbody that increases its chance for survival
191
What is directional selection
Individuals with alleles for a characteristics of an extreme type and more likely to survive and reproduce. This could be in response to an environmental change
192
What is stabilising selection
Individuals with alleles for characteristics towards the middle of the range are more likely to survive and reproduce.
It occurs when the environment isn’t changing and it reduces the range if possible characterists
193
How do you test the effect of antibiotics using agar plates
The bacteria you will use are likely to have been grown in a liquid broth (a mixture of distilled water, bacterial culture and nutrients).
Use a sterile pipette to transfer the bacteria from the broth to an agar plate (a Petri dish containing agar jelly). Spread the bacteria over the plate using a sterile plastic spreader.
Use sterile forceps to place paper discs soaked with different antibiotics spaced apart on the plate. Make sure you add a negative control disc soaked only in sterile water
Lightly tape a lid on, invert, and incubate the plate at about 25 °C for 48 hours. This allows the bacteria to grow (forming a 'lawn'). Anywhere the bacteria can't grow can be seen as a clear patch in the lawn
of bacteria. This is called an inhibition zone.
The size of an inhibition zone tells you how well an antibiotic works, the larger the zone the more bacteria were inhibited form growing.
A similar techniques can be used to test the effects of antiseptics or disinfectants on microbial growth
194
What are antiseptic techniques used when investigating bacterial growth
To prevent contamination of cultures by unwanted microorganisms.
This is important because contamination can effect the growth of the microorganisms you are working with
It’s also u,pirates to avoid contamination with disease causing microbes that could make you ill
195
What aseptic techniques should be used when testing the effects of antibiotics using agar plates
• Regularly disinfect work surfaces to minimise contamination. Don't put any utensils on the work surface.
Contaminated utensils should be placed in a beaker of disinfectant.
• Use sterile equipment and discard safely after use. E.g. glassware can be sterilised before and after use in an autoclave (which steams equipment at high pressure). Pre-sterilised plastics instruments are used once, then discarded.
• Work near a Bunsen flame. Hot air rises, so any microbes in the air should be drawn away from your culture.
• Minimise the time spent with the lid off the agar plate, to reduce the chance of airborne microorganisms contaminating the culture.
Briefly flame the neck of the glass container of broth just after it's opened and just before it's closed — this causes air to move out of the container, preventing unwanted organisms from falling in.
You should also take steps to protect yourself, e.g. wash your hands thoroughly before and after handling cultures.
196
What is the difference between genes and alleles
• Alleles differ between individuals of the same species
• All individuals of the same species will have the same genes
• You can have different frequency of alleles in a population
197
WhT is natural selection
Use rabbits as an example
- Have a population of identical rabbits
- Mutations allow variation to arise
- Having a population with diversity in their phenotypes ( eg, rabbits with different colored fur in a forest)
- Some characteristics are better suited for their environment , so a selection for a certain advantageous characteristic
- Individuals who don’t have the characteristic die out
- Individuals with characteristics will survive and reproduce and pass these genes /characteristics down to their offspring
- This happens over many generations
198
What is a genotype
The selection of genes an organisms has (alleles)
199
What is a phenotype
the characteristics expressed ( eg. hair colour), —it is also effected by the environment
200
Examples of a behavioral adaptation
Hibernating
201
Example of physiological adaptation
Temperature regulation
202
example of anatomical dapatatiom
Cacti have spines to prevent being eaten
203
In order for natural selection to occur there needs to be what within a population
Variation
204
What is genetic diversity determined by
The number of differnt alleles of a gene In a population
205
What 5 points do you need to make for a question on natural selection
• New alleles are brought about by mutations
• The new allele is advantageous and therefore organisms are more likely to survive
• And reproduce
• And pass on the advantageous allele to their offspring
• Therefore the frequency of the allele in the population will increase
206
What are new alleles brought about by
Mutations
207
What is the shape of the directional selection curve
BeLL curve
208
Does the curve change in directional selection
It doesn’t
The bell curve just shifts
209
Stabilising selection
Selection for the mean value
Extremes are selected agasit
210
Disrupted selection
For extremes
Medium is unflavoured
211
What is phylogeny
The study of the evolutionary history of groups of organisms
They tell us who is related to whom and how closely related they are to
212
T or f
All organisms have evolved form shared common ancestors
T
213
How can the fact that all organisms have evolved from shared common ancestors be shown
On a phylogenetic tree
214
What does the first branch represent on a phylogenetic tree
A common ancestor of all the family members
215
What does each of the following branched after the first beach represent om the phylogenetic tree
Represents another common ancestor form which a differnt group diverged
216
Closely related species on a phylogenetic tree diverged away From each other ……
Most recently.
( their branches are close together)
217
What is taxonomy
The science of classification
It involves naming organisms and organising them into groups
218
Why is classification important
Makes it easier to inventory and study
219
What do scientists now take into account what when classifying organisms
And how does they group organisms
Phylogeny
According to their evolutionary relationships
220
How many levels of group s are used to classify organisms
And what are they called
8
These groups are called taxa, each group is called a taxon
221
How are the groups arranged in taxonomy
Arranged in a hierarchy, with the largest groups at the top and the smallest group sat the bottom
Organisms can only belong to one group at each level in the hierarchy - there is no overlap
222
How are organisms first sorted in taxonomy
Into 3 large groups ( or taxa)
Called domains
223
What are the 3 domains
Eukarya
Bacteria
Archaea
224
What is the order of classification in taxonomy
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
225
T or f
As you move down the taxonomy hierarchy there are less groups at each level but more organisms in each group
F
There are more groups but less organisms in each group
226
Do the organisms in a group become more or less closely related in classification hierarchy
More closely related
227
Species definition
A species is a group if similar organisms able to reproduce to give fertile offspring
228
What group in the classification hierarchy contains only one type of organisms
Species
229
Why do scientists constantly update classification systems
Because if discoverues about new species and new evidence about known organisms
230
The nomenclature used for classification is called ….,,
Binomial system
231
What is the binomial system for classification
All organisms are given one internationally accepted scientific name,e in Latin and has 2 parts
232
What are the 2 parts of the binomial system for classification
The first part of the name is the genus name and has a capital letter
The second part is the species name and begins with a lower case letter
Names are always written in italics ( or underlined if handwritten)
233
Why is the binomial system used for classification
To avoid the confiscation of using common names
234
What is courtship behaviour
It’s carried out by organisms to attract a mate of the right species
235
Is courtship behaviour species specific
Yes
Only members of the same species will do and respond to the courtship behaviour.
236
What is courtship behaviour being species specific important
This allows members of the same species to recognise each other, preventing interbreeding and making reproduction more succssefull
( as mating with the wrong species won’t produce fertile offspring )
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Because of specificity of courtship behaviour , it can be used to do what
Classify organisms
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How is courtship behaviour used to classify organisms
The more closely related species are, the more similar their courtship behaviour
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Give some examples of courtship behaviour
Fireflies give off pulses of light. The pattern of flashes is specific to each species.
Crickets make sounds that are similar to Morse code, the code being different for different species.
Male peacocks show off their colourful tails. This tail pattern is only found in peacocks.
Male butterflies use chemicals to attract females. Only those of the correct species respond.
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What is variation
The differences that exists between individuals
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Is their variations between species or within species
Both
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What can variation be cause by
Genetic factors
Environment
Or a combo
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How can variation be caused by genetic factors
Differnt species gave differnt genes , which cause variation between species. Individuals of the same species have the same genes, but differnt alleles - this causes variation within a species
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Examples of how variation within a species can be caused but differnce in environment t
Climate
Food
Lifestyle
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When investigating variation you usually. Only Look at what
A sample of the population not the whole thing
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Why do you usually only. Take a sample of the population not the whole thing when studying variation
It would be too time consuming or impossible to catch all the individuals in the group.
So Samples are used as models for the whole population
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What should a sample be
To make sure the sample isn’t biased, it should be random
To ensure any variation observed in the sample isn’t just due to chancem it’s important to analyse the results statistically , this allows you to be more confident that the results are true and therfore will reflect what’s going on in the whole population
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What can you use to look for variation between species
Mean
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How to find mean
Total of all the values in your data
————————————————
The number of values in your data
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What does a normal distribution look like
As bell shapes graph
Most samples will include values either side of the mean
A Normal distribution is symmetrical about the mean
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What does the standard deviation tell you
How much the values in a single sample vary
It’s a measure of the spread of values about the mean
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What does a large distribution mean
The values in the sample vary a lot
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What does a small standard Deviation look like on a graph
All the values are similar and close to the mean , so the graph is steep
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What does a large standard Deviation look like on a graph
Here the values vary a lot
So the graph is fatter
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How can standard deviation be plotted on a graph of mean values
Using error bars
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What are error bars
They extend one standard deviation above and one below the mean ( so total length of an error bar is twice the standard deviation )
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What technology’s have been usefull for clarifying evolutionary relationships
Genome sequencing
Comparing amino acid sequences
Immunological comparisons
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What is conjunction
What one bacteria cell transfers dna to another bacteria cell
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How is antibiotic resistance directional selection
1) Variation - some strains of bacteria are resistant and some arnt
2) Competition - the non resistant bacteria are killed of by the penicillin
3) Survival of the fittest - the resistant bacteria survive
4) Passing on of genes - the resistant bacteria reproduce and pass on the adaptation to their offspring
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How is human birth weight is stabilising selection
The phenotypes with successful characteristic are preserved and those of greater diversity are reduced this selection doesn’t occur due to changes in the environment. If the environment stays the same then the individuals closest to the mean are favoured as they have the alleles that have given them the survival advantage . A new born babies weights, those with birth weight around 3kg are more likely to survive than the extremes.
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What is intraspecies variation
Differences within species
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How does evolution via natural selection work
- relies on mutation within species
- this variation is acted on by selection pressures
- only the fittest individuals survive to bree
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What is interspecies variation
Differences between species
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What is sampling
Take a selection of individuals form the targeted population
These individuals will represents the whole population
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What are the 2 problems with sampling
+ explain
Sampling bias - the selection process may be biased. The investigations may be making unrepresentative choices either deliberately or unwittingly
Chance - even if sampling bias is avoided the individuals chosen, by chance, may not be representative
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How can you avoid bias
Random sample - random number generator for coordinates
Use a large sample size and appropriate analysis of data collected will also help
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Learn the standard deviation equation
…
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What is Carl Linnaeus do
Grouped organisms by structure and characterists
Grouped organisms by the binomial system
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What is the binomial system
*The genus goes first with the capital letter
Followed by the species with a lower case
They are written in italics*
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What is a species
A group of organisms who share similar genes and can reproduce to produce fertile offspring
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What is phylogeny
The evolutionary relationship between organisms
- the phylogeny reflect the evolutionary branch that led to the organism
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What is the order of classification
Domain
Kingdom
Phylum
Class
order
Family
genus
Species
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What is the domain, kingdom, phylum and class for a mammle
Eukarya
Animalia
Chordata
Mammalian
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What 5 things are in the Chordata phylum
Fish
Reptiles
Amphibians
Mammals
Birds
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What can a phytogenic tree show
How closely organisms are related
Common ancestors
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When an evolutionary split occurs on a phytogenic tree
What is it called
Branching point or divergent point
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Why is courtship behaviour carried out
To attract the mate of the right species
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Eg
Of corurtshop behaviour
Releasing chemicals
Series of displayed ( eg, in birds)
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What is does it mean that courtship behaviour is species specific
only members of the same species will do and respond to that courtship behaviour. This allows members of the same species to recognise each other, preventing interbreeding and making reproduction more successful (as mating with the wrong species won't produce fertile offspring).
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As courtship behaviour is specific what can it be used to do
Classify organisms
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The more closely related species are, the more
……. Their courtship behaviour
Similar
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What can courtship behaviour be a way to do
6. Can be a way to signal reproductive maturity.
7. Way to for a bond with their pair, to increase reproductive success – not necessary for all species.
8. Synchronise mating with other individuals – in some species
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What are the Several different ways to investigate genetic diversity:
• Genome sequencing
• mRNA sequencing
• Amino acid sequencing
• Immunological comparisons
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Why is
• Genome sequencing
• mRNA sequencing
• Amino acid sequencing
• Immunological comparisons
More accurate then classifying organisms by appearance alone
because:
• The characteristics could be coded for by more than one gene.
• The same characteristics could have arisen separately.
• The characteristics could be influenced by the environment and not the genes.
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The difference between different species is called?
Interspecific
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What is genome sequencing
• use gene technology to read the base sequences of organisms. The genetic diversity of a species can be measured by sampling DNA.
• More closely related individuals should have less variation in the DNA base sequences.
• Huge advances have been made in this field in the last 50 years.
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What is mRNA sequencing
• Traits are due to genes being expressed, through expression mRNA is used.
• So by looking at mRNA we can see what genes are expressed and what they code for.
• More closely related organisms should have more similar mRNA sequence.
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What is amino acid sequencing
• The sequence of amino acids can also be studied as this can be taken back to the mRNA sequence and thus the DNA sequence.
• Related organisms have similar DNA sequences , hence similar amino acid sequences, hence similar proteins.
Example: cytochrome C is a short protein found in many species. The more similar the AA sequence is for cytochrome C the more closely the species is related.
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What are the 5 kingdoms
Bacteria
animals
Plants
Fungi
Protoctista
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What did Carl woese do
The 3 domain system
Used chemical analysis
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What are the 3 domains
Archaea
True bacteria
Eukaryotes
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What are archaea
Primitive bacteria
(Usually extremophiles)
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Biodiversity definition
The variety of living organism in an area
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Habitat definition
The place where an organism lives
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Community
All the populations of differnt species in a habitat
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What is local biodiversity
Variety of differnt species living in a small habitat that’s local to you
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What is global biodiversity
Variety of species in earth
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Where is biodiversity the greatest on earth
The equator
It decreases towards the poles
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What is species richness
A measure of the number of differnt species in a community
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How can species richness be worked out
By taking random samples of a community and counting the number of differnt species
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The number of differnt species in a community effect biodiversity,
What else?
The population size of those species too
(Species in a very small numbers shouldn’t be related the same as those with a bigger population )
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What the index of diversity another way of measuring
Another way of measuring biodiversity
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How is index of diversity calculated
using an equation that takes both the number of species In a community and the abundance of each species into a punt
N(N-1)
d= ———————
Sum of (n(n-1)
N- total number of organism of all species
n - total number of organisms of one species
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The number of species in community and the abundance of each species is also known as ….
T he species diversity
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The higher the index of diversity the ……,…… an area is
More diverse
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If all the individuals are of the same species the index of diversity is ….
1
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What farmin practices reduce biodivsity
1) Woodland clearance - thus us down to increase area of farmland, it directly reduces the number of trees and sometimes the number of different tree species. It also destroys habitats, so some species could lose their shelter and food source. This means that species will die or be forced to migrate to another suitable area, further reducing biodiversity.
2) Hedgerow removal — this is also done to increase the area of farmland by turning lots of small fields into fewer large fields. This reduces biodiversity for the same reasons as woodland clearance.
3)Pesticides — these are chemicals that kill organisms (pests) that feed on crops.
This reduces diversity by directly killing the pests. Also, any species that feed on the pests will lose a food source, so their numbers could decrease too.
4) Herbicides — these are chemicals that kill unwanted plants (weeds). This reduces plant diversity and could reduce the number of organisms that feed on the weeds.
5) Monoculture — this is when farmers have fields containing only one type of plant. A single type of plant reduces biodiversity directly and will support fewer organisms (e.g. as a habitat or food source), which further reduces biodiversity.
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What are some examples of conservation schemes to protect biodivsirty
• Giving legal protection to endangered species.
• Creating protected areas such as SSSis (Sites of Special Scientific Interest) and AONBs (Areas of Outstanding Natural Beauty). These restrict further development, including agricultural development.
• The Environmental Stewardship Scheme which encourages farmers to conserve biodiversity, e.g. by replanting hedgerows and leaving margins around fields for wild flowers to grow.
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How have advances in techniques of genome sequences clarify evolutionary relationships
Genome sequencing — Advances in genome sequencing have meant that the entire base sequence of an a higher percentage of similarity in their DNA base order, e.g. humans and chimps share around 94%, humans and mice share about 86%.
Genome sequencing has clarified the relationship between skunks and members of the Mustelidae family leg weasels and badgers). Skunks were classified in the Mustelidae family until their DNA sequence was revealed in be significantly different to other members of that family. So they were reclassified into the family Mephitida.
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How have advances in techniques of comparing amino acid sequecnes clarify evolutionary relationships
Comparing amino acid sequence — Proteins are made of amino acids. The sequence of amino acids in a protein is coded for by the base sequence in DNA (see p. 82). Related organisms have similar DNA sequences and so similar amino acid sequences in their proteins. E.g. cytochrome C is a short protein found in many species. The more similar the amino acid sequence of cytochrome C in two different species, the more closely related the species are likely to be.
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How have advances in techniques of immunological comparisons clarify evolutionary relationships
Immunological comparisons — Similar proteins will also bind the same antibodies (see p. 44).
E.g. if antibodies to a human version of a protein are added to isolated samples from some other species, any protein that's like the human version will also be recognised (bound) by that antibody.
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What where early estimates of genetic diversity were made by
looking at the frequency of measurable or observable characteristics in a population
Since differnt alleles determine differnt characteristics a wide variety of each characteristic in a population indicated a high number of differnt alleles and so a high genetic diversity
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How have gene technologies allowed us to measure genetic diversity directly
For example:
• Different alleles of the same gene will have slightly different DNA base sequences.
Comparing the DNA base sequences of the same gene in different organisms in a population allows scientists to find out how many alleles of that gene there are in that population.
Different alleles will also produce slightly different mRNA base sequences, and may produce proteins with slightly different amino acid sequences, so these can also be compared.
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What do new technology to measure genetic diversity directly allow a
Accurate estimates
Also allow the genetic diversity of differnt species to be compared more easily
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Impact of agriculture
Agriculture ecosystems controlled by humans, farmers select 1 species so reduced genetic variety by reducing alleles to the ones they desire
It’s economical to take up a large area , give little space for anything else
Competition and addition of pesticides adds up to a loss of species diversity
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What does biodiversity reflect
How well an ecosystem functions
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The higher to species diversity index to …… stable the ecosystem usually is
More
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What will effect an ecosystem
A change in climate
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Why is an ecosystem with a higher diverts index more stable to change in conditions
More likely to have at least one species which may survive a change in conditions
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Is the species diversity index low or high in extreme environments
And why
Low
Only few species have necessary adaptations to survive harsh conditions
Usually results in an unstable ecosystem, the species community are dominated by the climate
Rather than the species within them
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Definition of species diversity
Refers to the number of differnt species and the number of individuals species within a community
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Definition of genetic diversity
Refers to the variety of genes posses by the individuals that make up any one species
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Definition of ecosystem diversity
Refers to the range of differnt habitats within a particular area
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What is biodivisty
General term used to describe the variety of the living world
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What is usefull to know to find biodiversity
Number of differnt species in a given area
The proportion of the community that is made up of an individual species
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What is the diversity index calc
N ( N - 1 )
D = ———————
Sum of (n - 1 )
N- total number of all species (add up frequencies)
n - total number of organisms of each species
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Limitations of the old sequencing techniques
Expensive and inefficient
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Advantages of new sequencing
(Next gerneTion sequencing)
- many happen at same time
- micr scale
- fast
- low cost
- shorter length
- step towards personalised medicine
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Uses of sequencing
- knowing the sequence of genome for a pathogen
- doctors can find source of infection
- identify antibiotic resistant strains of bacteria
Track progress of an outbreak
Indenting regions of a pathogen r that may be useful to target in development of drugs
