Genetic Information, Varietion And Relationships Between Organisms Flashcards
Compare eukaryotic and prokaryotic DNA cells
- both made up of dna nucleotides containing deoxyribose, phosphate group and a nitrogenous based
- nucleotides joined together by phosphodiesterbhonde to make a polymer chain
- eukaryotic cells are longer where prokaryotic cells are shorter
- eukaryotic cells are linear where prokaryotic are circular
- eukaryotic cells are associated with histones where prokaryotic cells aren’t
What is the name for DNA wrapped around histones?
Nucleosomes
Similarities between dna in mitochondria/ chloroplast and prokaryotic cells
- short
- circular
- not associated with a protein
What is a gene
- a base sequence of DNA that codes for the amino acid sequence of a polypeptide and a functional RNA
What is a locus
- exact position of a gene on a chromosome
What is a triplet
- a sequence of 3 DNA bases that code for a specific amino acid
What are the 3 features of the genetic code?
- degenerate, universal and non overlapping
What is meant by degenerate?
- different base sequences code for the same amino acid
What is meant by universal?
- same base triplet code for the amino acid
What is meant by non overlapping?
- each base is only read once and only part of one triplet
Why is degeneracy an advantage?
- if there is a mutation , even if the base triplet is different it may still code for the same amino acid
Why is non overlapping an advantage?
- if there is a mutation, it will only affect 1 codon minimising the harm done
What is an intron
- sections of DNA that don’t code for polypeptide found in eukaryotic DNA but not prokaryotic
What are exons?
- sequences of DNA that code for amino acids
What is a codon?
- 3 bases on mRNA and jay for for w specific amino acid
What is a start codon?
- three bases at the start of every gene that initiate translation
What is a stop codon?
- three bases at the end of every gene that cause ribosomes to detach and stop translation
What is meant by genome
- complete set of genes in a cell
What is meant by a proteome?
- full range of proteins a cell can produce
What is mRNA?
- short, single polynucleotide strand found in the cytoplasm and nucleus. Has codons complimentary to anticodons on tRNA
What is tRNA
- single polynucleotide strand folded into a clover leaf shape joined together by H bonds. Has an amino acid binding site and a binding site where it’s anticodons bind with their complimentary codons on mRNA
Describe the process of transcription
- DNA Helicase breaks H bonds between complimentary base pairs and unzips double strand
- Only one DNA strand acts as a template for mRNA production
- RNA nucleotides attracted to exposed bases
- RNA polymerase joins nucleotides together
- Pre mRNA is spliced to remove introns
Explain the process of Translation
- Ribosomes attached to mRNA
- Ribosomes move to start codon
- tRNA molecule carries specific amino acid and the anticodon on tRNA pairs with complimentary codon on mRNA
- Ribosome moves along to the next codon and can only fit 2 tRNAS
- Amino acids join to form peptide bonds
What is a gene mutation?
A change in the base sequence of DNA, randomly occurs during DNA replication
What is deletion mutation?
- the base in a triplet is removed from the sequence causing a frame shift to the left
What is a substitution mutation?
- base is replaced by another, may have no impact on new codon as it may still code for the same amino acid as it is degenerate
What is a non disjunction?
- chromosomes or chromatids don’t split equally during anaphase
What are the 2 forms of disjunctions
Polyploidy - changes in the whole set of chromosomes
Aneuploidy - changes in number of individual chromosomes
What is meiosis
- involves 2 nuclear divisions and creates 4 haploid daughter cells from a single parent cell
What are the 2 mechanisms that allow variation in meiosis?
Independent segregation
Crossing over
What is independent segregation
- homologous pairs of chromosomes line up opposite eachother at the equator of the fell and are randomly separated, one of each homologous pair ends up in the Daughter cell
What is crossing over
- homologous pairs line up opposite each other at equator, chromatids can be twisted around putting tension on the chromatids, causing parts of it to break. Broken parts recombine with other chromatids resulting in new combinations of alleles
What is the difference between meiosis and mitosis
Meiosis involves 2 nuclear divisions, results in 1 haploid cell and has genetic variation where mitosis has 1 nuclear division, results in diploid cells and cells are genetically identical.
Describe the process of natural selection
- New alleles for gene created by random mutations
- More alleles for a gene increases survival chance in that environment thus more likely to reproduce
- Advantageous alleles are passed down generations
- Over many generations, allele frequency increases in the population.
What is evolution?
The change in allele frequency over many generations in a population
What are the types of adaptations?
- anatomical, physiological and behavioural
What are the types of selection
Directional, stabilising
What is directional selection?
- selective advantage is an extreme
- occurs when there’s a change in environment
E.g. antibiotic resistance is either very high or very low
What is stabilising selection
- modal trait has selective advantage
- no change in environment
- standard deviation decreases
E.g. human birth rates
Describe courtship
- Recognising of same species ensures production of fertile offspring and prevents interbreeding
- Identifying a mate that’s capable of breeding, meaning they are both sexually mature, fertile and receptive to breeding
- Forming a pair bond ensures a successful upbringing of the offspring
- Synchronising of mating ensures mating occurs when there’s a maximum probability of sperm and egg meeting
- Bringing the he opposite sex into a physiological state that allows breeding
What is a hierarchy?
- smaller groups arranged within larger groups with no overlap between groups
What is the order of the taxonomic hierarchy?
Domain, Kingdom, phylum, class, order, family, genus, species
What are the two names involved in a species binomial?
Genus, species
What is biodiversity
Range and variety of genes, species and habitats within a particular region
What is species diversity?
Number of different individuals within each species in a community
What is genetic diversity?
Variety of genes amongst all individuals in a population of a species
What is ecosystem diversity
Range of different habitats
What is species richness
Number of different species in a community
What are different farming techniques
- destruction of hedgerows
- selective breeding
- monocultures
- overgrazing
- filling in ponds and draining wetlands
What does N and n stand for
N - total number of organisms of all species
n - total number of organisms in a particular species
