Topic 4 - Genetic variance and biodiversity Flashcards
What is a gene mutation ?
Mutations
A spontaneous change in the DNA sequence of chromosomes.
What are 4 types of mutations ?
Mutations
- Substitutions - one base is substituted with another.
- Additions - one base is added.
- deletions - one base is deletion.
- non disjunction- a chromosome does not fully divide during meiosis.
Why can substitions not always cause changes in the primary structure of a protein ?
Mutations
Beacuse the genetic code is degenerate.
Why do additions and deletions usually always cause changes in the primary sequence of a protein ?
Mutations
Because it changes the number of bases that are present therefore it causes a frameshift
What are mutagenic agents ?
Mutations
things that increase the rate of mutations, e.g. ultravoilet radiation, ionising radiation and some chemicals and viruses.
What are chromosome mutations ?
Mutations
It can arise spontaneously by chromosome non-disjunction during meiosis. Individual pairs of chromosomes fail to separate, it leads to gametes having more or less chromosomes.
What occurs during down syndrome ?
Mutations
It is caused by a person having an extra chromosome 21, or part of it. It fails to separate during meiosis and one cell gets an extra copy . When it gets fertilised it results in the zygote has 3 chromosome 21.
What is a diploid cell ?
Meiosis
- Normal body cells with cell with 2 of each chromosome, one from the male and one from the female.
- 46 chromosomes.
- 2n
What is a haploid cell ?
Meiosis
Gametes with 23 chromsomes
theres one copy of each chromosome
n
What is a zygote ?
Meosis
A zygote cell is produced when a haploid sperm cell fertilises a haploid egg cell to form a diploid cell which divides to develop into a new organism.
What does ‘fertilisation is random’ mean and what happens as a result of this ?
Meiosis
- Any sperm cell can fertilize any egg cell.
- Random fertilisation produces zygotes with different combinations of chromosomes.
- Mixing genetic material increases genetic diversity within a species
Explain the stages of meiosis
Meiosis
- Interphase: DNA unravels and replicates. ATP content increases and organelles also replicate.
*Meiosis I - Prophase I: Chromones condense, getting shorter and fatter forming homologous chromosomes. Centrioles move to opposite poles of the cell forming a network of spindle fibres. The nuclear envelope disintegrates and the nucleolus disappears. Crossing over may occur.
- Metaphase I: The homologous pairs line up along the equator of the cell, attached to the spindle fibres by their centromere. Independent segregation may occur here.
- Anaphase I: The centromeres divide, splitting the homologous pais of chromomes. Spindle fibres contract, pulling the chromosomes to opposite ends of the cell.
- Telophase I: Chromosomes reach opposite poles of the cell and uncoil, becoming long and thin . A nuclear envelope forms around the 2 sets of chromosomes, forming 2 nuclei.
- Cytokinesis I: The cytoplasm divides, forming 2 genetically different cells.
Meiosis II - Prophase II: Chromones condense, getting shorter and fatter forming pairs of sister chromatids attached at the centromere. Centrioles move to opposite poles of the cell forming a network of spindle fibres. The nuclear envelope disintegrates and the nucleolus disappears.
- Metaphase II: The chromosomes line up along the equator of the cell, attached to the spindle fibres by their centromere.
- Anaphase II: The centromeres divide, chromomes. Spindle fibres contract, pulling the sister chromatids to opposite ends of the cell.
- Telophase II: Chromosomes reach opposite poles of the cell and uncoil, becoming long and thin. A nuclear envelope forms around the 4 sets of chromosomes, forming 4 nuclei.
- Cytokinesis II: The cytoplasm divides, forming 4 genetically different halploid cells.
What is crossing over in prophase I ?
Meiosis
- Homologous pairs of chromosomes pair up, the chromatids twist around each other and some parts may swap.
- This means that each of the 4 daughter cells contains chromatids with different allleles, increasing genetic variation.
- occurs between non sister chromatids.
What is independent segregation in metaphase I ?
Meiosis
- It is completely random which of the chromosomes end up in each daughter cell.
- As a result each daughter cell has a different combination of maternal and paternal chromosomes, increasing genetic variation.
During meiosis, which things lead to increased genetic variation ?
Meiosis
Crossing over during prophase I and independent segregation during metaphase I.
What are the differences between mitosis and meisosi ?
Cell Division
- In mitosis, cell division occurs once, however in meiosis, cell division occurs twice.
- In mitosis cells that are produced are diploid and therefore have the same number of cells as there parent, however in meiosis, cells that are produced are haploid and therefore have half of the amount of cells that their parent cell had.
- In mitosis 2 daughter cells that are genetically identical are produced, however, in meiosis, 4 daughter cells that are genetically different are produced.
- Mitosis is asexual reproduction, meiosis is sexual reproduction.
What is genetic diversity ?
Genetic Diversity
The number of different alleles of genes in a specific population.
What are the sources of genetic variation ?
Genetic Diversity
- mutations
- fusion of gametes
- independent segregation
- crossing over
- gene flow
What are the three types of adaptations ?
Natural selection
Behavioural
Pysiological
Anatomical
What are behavioural adaptations ?
Natural selection
Ways and organism acts which increases its chances of survival and repproduction, e.g. possums play dead to escape from attack by their predator.
What are pysiological adaptations ?
Natural selection
Processes insdie an organisms body that gives it an increased chnace of survival and reproduction, e.g. when brown bears hibernate in winter, their rate of metabolism decreases to conserve energy.
What are anatomical adaptations ?
Natural selection
Structural features on an organsims body that give it a better chance of survival and reproduction, e.g. whales have a layer of thick blubber that keep them warm in the cold sea.
What are the 2 types of selection ?
Natural selection
Directional
Stabalising
How does natural selection and evolution work ?
Natural selection
- A random mutation occurs within an organism resulting in a new allele.
- Most mutations are harmful, however, in certain envitonments, the new allele of a gene may benefit the organism, leading to increased reproductive success.
- The advantageous gene is inheritied by members of the next generation.
- Over many generations, the new allel increases in frequency in the population (evolution).
What is directional selection and its example ?
Natural selection
Individuals with alleles for extreme characteristics are more likely to survive and reproduce.
E.g. Antibiotic resistance. Some individuals in the population have an allele for antibiotic resistance due to a random mutation. The population is exposed to antibiotics and the bacteria with the resistant allele survive and have increased reproductive success, the advantageious allele is then inheritied to the next generation. Overtime, the new allele increases frequency in the population.
What is stabalising selection and its example ?
Natural selection
Individuals with alleles for characteristics in the middle of the range are more likely to survive and reproduce.
E.g. Human birth wieght. Smaller and larger babies have less chance of survival , meaning that the conditions are favourable for medium sized babies, so the weight of human babies tends to shift towards the middle of the range.
What would the graph for directional selection show ?
Natural selection
The offsprings’ graph line would shift to the right (higher end of the range).
What wold the graph for stabalising selection show ?
Natural selection
The offsprings’ graph line would shift towards the middle of the range.
Describe the appearance of a pair of chromosomes in meiosis I
Meiosis
The chromatids are joint together by the centromere due to DNA replication.
What is intraspecific competition ?
Natural Selection
Competition between the same species.
What is interspecific competition ?
Natural Selection
Competition between different species.
What makes organisms apart of the same species ?
Courtship
Organisms that are able to interbreed and produce fertile offspring are apart of the same species.
What is courtship ?
Courtship
Pre-mating activies for simulation, partner attraction and for mating initiation.
What is the process of courtship ?
Courtship
- The female comes into season
- The male displays a ritual
- The female responds with a signal for mating to begin.
- If not the male goes elsewhere to try again
- This ensures for succesful mating.
Why do courtship rituals occur ?
Courtship
- For species recognition.
- For idenitification of a mate that is capable of breeding (fertile female).
- Ensures stimulation and sinnchronization of mating
What are some examples of courtship behaviour ?
Courtship
- Fireflies give off pulses of light.
- Crickets make songs like morse code.
- Male peacocks show off their colourful tails.
- Male butterfiles release chemicals.
How can u tell how closely relates species are by analysing courtship.
Courtship
The more cloesly related the species is, the more similar the courtship behviour will be.
What is phylogenic classification and what does it do ?
Classification
- The study of the evolutionary history of groups of organisms.
- It helps us tell what organisms are related and how closely related they are.
What is a taxon ?
Classification
A level of classification
What is a hierarchy in relation to classification ?
Classification
- The arrangement of groups in order.
- Smaller groups within larger groups.
- No overlapp.
What is the list of phylogenic hierarchy in order ?
Classification
- Domain (eukayote,prokaryote & archae)
- Kingdom
- Phylum
- Class
- Order
- Family
- Genus
- Species
What is the binomial naming system ?
Classification
- All organisms are given an internationally accepted scientific name in latin that has 2 parts.
- The first part is the Genus with a capital letter
- The second part is the species in lower case
- Underline it when written.
What is meant by a phylogenic group ?
Classification
Evolutionary links / common ancestory between organisms
What are 3 techniques that can clarify evolutionary relationships ?
DNA Technology
Genome sequencing
Comparing amino acid sequencing
comparing mRNA
What is genome sequencing ?
DNA Technology
The base sequence of an organism’s DNA can be determined and compared to another organisms DNA base sequence to see how closely related they are. The higher percentage of similarity there is, the more closely related they are.
What is comparing amino acid sequencing ?
DNA Technology
Related organisms have similar DNA and therefore code for similar proteins, resulting in them having similar proteins.
What is gene technology ?
DNA Technology
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 will allow scientists to determine how many alleles of a gene there are in a population.
How did genetic diversity be assessed in the past ?
DNA Technology
Estimates were made by looking at the frequency of measurable, observable characteristics in a population, e.g. eye colour.
What is Biodiversity ?
Biodiversity
The range and variety of genes, species and habitats within a particular region.
What is a habitat ?
Biodiversity
The place where an organism lives
What is a community ?
Biodiversity
All the populations of different species in a habitat.
What is local biodiversity ?
Biodiversity
The variety of different species living in a small habitat that’s local to you.
What is global diversity ?
Biodiversity
The variety of species on earth.
What is species richness ?
Biodiversity
The number of different species in a community.
What is species diversity ?
Biodiversity
The number of species in a community and the abundance of each species in any community.
What is habitat diversity ?
Biodiversity
The range of different habitats within a particular area.
How can you investigate biodiversity accurately ?
Genetic variation
- Use a large sample.
- Use a random number generator to generate random coordinates for sampling
- Analyse the results statistically to ensure that the variation is not due to chance.
What do conservationists do?
Biodiversity
protect biodiversity
What are some exmples of conservation schemes ?
Biodiversity
legal protection to endangered species.
creating protected areas, restricting agricultural develpment.
List methods that farmers use that reduce bio diversity.
Biodivesity
- woodland clearance - reduce number of trees
- hedgerow removal - turining lots of small fields into larger fields
- pesticides - chemicals that kill organisms that feed on crops.
- herbicides - chemicals that kill unwanted plants.
- monoculture - farmers have fields containing only one plant.
What are the 3 ways to evaluate evolutionary relationships ?
- genome sequencing
- amino acid sequence
- immunology
What is immunological comparison ?
similar proteins will bind to the same antibody
how would you estimate the number of plants in a field
- measure the perimeter with a tape measure
- use a random number generator to generate 15 coordinates
- place a quadrat at every coordinate
- count the number of plants in each quadrat
- calculate the mean
- multiply by the area of the field
