Genetic Information, Variation And Relationship Betweeb Organisms 4 Flashcards
What is loci
Position of gene on chromosomes
Why are chromatids identical
Genes are at the same locus
What is the genetic code
The sent of rules by which information encoded in genetically material is translated into proteins by living cells
Explain the 3 features of the genetic code
NON OVERLAPPING: Each base is part of only one Triplet
DEGENERATE CODE: One amino acid can be coded for by more than one Triplet
UNIVERSAL CODE: The same Triplet codes for the same amino acid in all living organisms
What is another name for Triplet
Codon
What is beneficial about the genetic code being degenerate
If point mutation occurs, even though the Triplet of bases will be different, it may still code for the same amino acid and therefore have no effect
Why is non overlapping in genetic code beneficial
If point mutation occurs, it will only affect one codon and therefore one amino acid
What are introns and exrons
Introns are non coding base sequence
Exrons are coding base sequence
What happens during splicing
Introns are removed, extrons join together to form mRNA
Define genome
The complete set of genes in a cell
Define proteome
The full range of proteins a cell is able to produce
Why can’t DNA leave the nucleus
It is too big and there and there are enzymes in the Cytoplasm which could damage it
What are the two steps in protein synthesis
Transcription and Translation
Explain the process of transcription
-DNA helicase breaks Hydrogen bonds between bases causing DNA double helix to unwind
-One of the strands of DNA produced acts as a template
-Free nucleotides assemble along the strand of DNA according to the base pairing rule so complementary bases join
-RNA polymerase joins together RNA nucleotides by catalysing formation of phosphodiester bonds
-This makes premRNA
-Introms are spliced out to make RNA
Explain the process of translation
-mRNA binds to the ribosome in Cytoplasm
-tRNA moelcules bring specific amino acids to the ribosome
-tRNA’s anticodons bind to complementary codons on the mRNA by forming Hydrogen bonds
-ATP provides energy for the formation of peptide bonds between amino acids
-tRNA is released after amino acids join to form a polypeptide
What is meiosis
A type of cell division that produces 4 daughter cells with a haploid chromosome number
Where does meiosis occur
Sex cells
Haploid sperm + Haploid egg
Diploid zygote
What is an allele
Different versions of a gene
What is a diploid cell
Two complete sets of Chromosomes
What is a haploid cell
One complete set of Chromosomes
Explain all the steps in meoisis
PROPHASE 1
-Chromatin condenses and becomes shorter and thicker and this forms two sister chromatids joined together at the centromere
-Homologous Chromosomes pair up to form bivalent
-Crossing over occurs between non sister chromatids of Homologous Chromosomes resulting In exchange of alleles which produces new combination of alleles (happens af chiasma)
METAPHASE 1
Chromosomes line up along equator of cell randomly
ANAPHASE 1
-Spindle fibres contract
-Chromosomes from each pair move to opposite poles
-Centromeres do not divide so each chromosome is still 2 sister chromatids
TELOPHASE 1
-Chromosomes decondense
-Nuclear membrane reforms around 2 groups of Chromosomes
-Cytoplasm divides
-Short period where no action occurs (interkinesis)
PROPHASE 2
-Chromatin condenses
-Nuclear envelope breaks down
-Cell has a haploid number of Chromosomes
METAPHASE 2
-Chromosomes line up along the equator
-Spindle fibres from opposite poles attach fk each sister chromatid
ANAPHASE 2
-Centromere divides and sister chromatids become independent as they move to opposite poles of the cell
TELOPHASE 2
-Chromosomes decondense
-Nuclear membrane reforms
-Cytokinesis occurs
-Each of the 4 new cells produces are genetically different
What is haploid and diploid represented by
Haploid(n)
Diploid(2n)
What is the function of meiosis
Sexual reproduction
What is the function of mitosis
Growth and repair
What are 2 types of nondisconjunction
Failure of Homologous Chromosomes separating during meiosis I
Failure of sister chromatids sepersting during meiosis II
How does nondisconjuction affect number of Chromosomes in gametes
Produces gametes with incorrect number of Chromosomes
What is a mutation
A chnage in the base sequence of DNA
What is a substitution mutation
Chnage in a single nucleotide base
Whar is messence substitution
Substitution that results in a single amino acid change
What is a nonsense mutation
A substitution that results in a stop codon instead of an amino acid usually resulting a non functional protein
What two types of mutations cause frameshifts
Addition and deletion
What are the 3 types of substitution mutations
Silent mutations
Missense mutations
Nonsense mutations
What is a silent mutation
It doesn’t change the amino acid sequence of the polypeptide
[6 marks] How does mutation form a non functional enzyme
Chnage in base sequence
Change in amino acid sequence
Change in Hydrogen/ionic/disulfide bonds
Chnage in tertiary structure
Chained in shape of active site
Substrate can no longer bind to enzyme as they are not compelemtary so enzyme substrate complex is no longer formed
Why are frameshift mutations very harmful
All the subsequent triplets are chnaged so chnaged triplets could code for different amino acids resulting in a very different sequence of amino acids resulting in a non functional protein
What is translocation in terms of mutations
A section of bases on one chromosme detaches and attaches onto a different chromosome
This can cause significant impacts on gene expression and therefore the resulting phenotype
What factors cause genetic variation within species
-Crossover
-Independent assortment
-mutation
-gametes fusing randomly during fertilisation
What is genetic diversitiy/variation
Sym of different alleles of genes in a population
What needs to be present for natural selection to occur
Genetic diversity
Explain the process of natural selection
-There is genetic variation in individuals of the same species due to random mutations
-Some alleles give an advantage and individuals with the advantageous alleles are more likely to survive and reproduce
-This passes on the advantageous alleles to offspring
-This increases allele frequency of the advantageous alleles
What are two types of natural selection
Stabilising selection
Directional selection
Explain directional selection
-Change in environment
-One of the extremes has the selective advantage
-Individuals with alleles for characteristics of an exteme type are more likely to survive and reproduce
Explain stabilising selection
-No change in the environment
-Favours alleles around the middle
-Individuals with alleles for charectersjtics towards the middle of the range are more likely to survive and reproduce
Natural selection Samsung notes
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Whar is included in the binomial system
Genus species
Define classification
Putting organisms into groups based on their similarities and differences
In classification, what are the groups called
Taxon
Why do different species look similar
Love in similar environments
Have similar selection pressures
Similar alleles will have the selection advantage
Produces similar/same proteins and therefore have similar characteristics
Name all the taxa in order
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Define hierarchy
Smaller groups arranged within larger groups
No overlap betweeb groups
What are the 3 domains
Bacteria
Archaea
Eukarya
What was the original way to classify and what is it now
Differences that are obvious like appearance and behaviour and fossils
Now is dna sequence, mrna sequence, amino acids sequence, immunological
What diagram is used to show phylogenic relationships
Phylogenic trees
What does phylogeny show
Who’s related to who and how closely related they are
The evolutionary relationship between organisms
Explain the domain bacteria
70s Ribosomes
Unicellular
Cell wall not made from cellulose
Single loop of dna but no histone unit
Explain the domain eukarya
Mainly multicellular
Cells co tain membrane bound organelles
Membranes Contain fatty acids linked to glycerol via ester bonds
80s Ribosomes
Cell wall not made from murein
Explain the domain archaea
No murein in cell wall but does have a cell wall
70s Ribosomes
Cell membranes have fatty acids linked to glycerol via ester bonds
What are the 3 different measures for biodiversity and define them
SPECIES DIVERISTY The number of different species and individuals either each species in a community
GENETIC DIVERSITY The variety of genes among all the individuals in a population of one species
ECOSYSTEM DIVERSITY The range of different habitats
Define species richness
Number of different indivudal species in an environment
What is courtship behaviour
Necessary precursors to successfyl mating
Can be simple (visual/auditarh/chemical stimuli) or complex
Explain courtship in drosophila
Male vibrates it’s wings, alters body position, licks female
If index diversity is high, what evidence would there be
More plant species
More variety of food
More habitat
What does it mean when the index of diversity is closer to 10
Species diversity is high
What is a decrease in biodiversity usually caused by
Human activity
What are some reasons why farming reduces biodiversity
Destruction of hedgerows
Selective breeding
Monocultures
Overgrazing
Filling in ponds and draining wetlands
Why do we do sampling
It is more time efficient and if implemented correctly, it can be more accurate
How do you ensure samples accurately represent the population
Large sample
Random sampling so it is not biased
What is the formula used in sampling
(Area of field/Area of quadrat) X 100
What sampling do you use for slow moving/non motile organisms compared to motile organisms
Slow moving/non motile organisms - Sampling using a quadrant
Motile organisms - Sampling using the mark release recapture method
During sampling, when would you use random sampling and a line transect
Random - uniform distribution
Transect - uneven distribution
Explain how you do random sampling with a quadrat
Lie two tape measures at a right angle to create a gridded area
Use a random number generator to generate two coordinates
Place the quadrat and collect data
Repeat at least 30 times and calculate a mean
Explain the two types of transect
Belt transect - The quadrat is placed at every position along the tape measure
Interrupted belt transect - the quadrat is placed at uniform intervals along the tape measure
Explain how you use the line transect method
Place the tape measure at a right angle to the shore line
Place the quadrat at every position/regular intervals
Collect the data in each quadrat
Repeat by placing another 30 transects along the beach at right angles to the shore line
Explain the the 3 methods to estimate the abundance of a species
Local frequency - percentage of squares in the quadrat with the species present
Density - The number of one species in a given area
Percentage cover - proportion of the ground occupied by the species
What is monoculture
Growing one species
Define hedgerow
Line of shrubs/trees that border a peice of land with herbaceous plants at the base
What are the advantages of hedgerow
-Greater biodiversity which increases predators of pests which increases crop yield which increases income
-Attracts more tourists which increases income
What are some disadvantages of hedgerows
-Reduced land area so less crop growth and less food
-More pests so less crop yield and lower income for farmer
-Very difficult to farm so less income
Why do you leave spaces between hedgerows
Prevent spread of pests
Farmer can maneuver with farm equipment
