Module 4 - Genetic info, variation and relationships between organisms Flashcards
Biodiversity
Variety of habitats and species in an area
Species diversity
Number of different species and individuals in a species
Genetic diversity
Variety of alleles in a population
Larger number of individuals in a species, larger the genetic diversity
Benefits of high species diversity
Stable ecosystem
Species less likely to become extinct
Extinction won’t affect food chain as there are other species available
How to measure species diversity
Species diversity index Diversity = N(N-1) / £n(n-1) N = number of individuals in a population n = number of individuals in a species £ = sum of
How does deforestation lower species diversity
Decrease plant species diversity
Less variety of habitats
Less variety of food sources
Decrease animal species variety
How does farming lower species diversity
Deforestation for space for farm
Only grow a few plants and animals and selectively breed
Pesticides to kill other species
What is natural selection and adaptation
Variation in population of a species
Random mutation = new allele
Selection pressure applied
New allele means better chance of survival
Reproduction so frequency of new allele increases
At expense of old allele
Stabilising selection
Environment favours most common characteristic
Extremes die out
Birth weight
Directional selection
Favours an extreme
Over time becomes most common characteristic
Normal distribution shifts to that extreme
Antibiotic resistance
What is a gene
Section of DNA coding for a protein
What are genes made of
Introns (non-coding)
Exons (coding)
How does a gene code for a protein
Made out of a sequence of bases
3 bases code for 1 amino acid
sequence of bases determine triplet codes
Determine sequence of amino acids
Properties of triplet code
Degenerate = each amino acid has more than 1 triplet code Non-overlapping = each base is only read once Universal = each base sequence codes for the same amino acid in all species
Types of mutations
Insertion
Deletion
Substitution
DNA VS RNA
Deoxyribose vs ribose sugar
Thymine vs uracil
Double stranded vs single stranded
One type vs 2 types
mRNA
Messenger RNA
Single stranded complementary copy of a gene
Carries code for assembling protein (codon)
tRNA
Transfer RNA
Single stranded RNA folded and held by hydrogen bonds between bases
Amino acid attachment site on top
3 specific bases on bottom (anticodon)
Anticodon binds to complementary codons on mRNA
Transcription (not process)
Occurs in nucleolus
Produces mRNA
Template strand used to build mRNA
Transcription process
DNA helicase breaks hydrogen bonds between bases
Strands separate
Complementary bases bind to bases on the template strand
RNA polymerase joins sugar phosphate backbone
pre-mRNA spliced to remove introns
Leaves nucleus towards ribosome
Translation (not process)
Takes place on ribosomes of rough endoplasmic reticulum
Uses sequence of codons on the mRNA to assemble the protein
Translation process
mRNA leaves nucleus via nuclear pore
Attaches to ribosome
Complementary tRNA carrying specific amino acids bind to codons with their anticodons
Another tRNA molecule binds
Amino acids joined by peptide bonds
First tRNA molecule detaches from amino acid and leaves ribosome
Role of ATP in protein synthesis
Adding an amino acid to a tRNA molecule