Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
106 Cards in this Set
- Front
- Back
|
Describe the steps of mitosis |
• Beforehand, DNA unravels and replicates forming two copies of each chromosome, called chromatids • DNA condenses to form double-armed chromosomes, each made of two sister chromatids joined by a centromere • Meiosis 1 begins • Chromosomes arrange themselves in homologous pairs • Homologous pairs line up on cell equator • Attach to spindles by fibres and are pulled to opposite poles (one chromosome to each side) • Cytoplasm splits and nuclear envelopes form, producing 2 diploid cells • Meiosis 2 begins • Chromosomes line up on cell equator • Attach to spindle fibres by centromere and pulled to opposite cell poles • Cytoplasm splits and nuclear envelopes form, producing two haploid cells • All together 4 genetically different haploid cells are produced |
|
|
How does crossing over increase genetic variation? |
• Chromatids from homologous pairs of chromosomes cross over • Genetic material is swapped • Chromatids contain the same genes, but now have a different combination of alleles |
|
|
How does independent segregation of chromosomes increase genetic variation? |
• It is completely random as to which chromosome ends up in each daughter cell • Four daughter cells produced have completely different combinations of maternal or paternal chromosomes |
|
|
How many daughter cells are produced during meiosis |
4 |
|
|
How is genetic variation increased during meiosis? |
Independent segregation of chromosomes Crossing over of chromatids |
|
|
What is the outcome of mitosis? |
• Produces cells with the same number of chromosomes as the parent cell • Daughter cells are genetically identical • Two daughter cells produced |
|
|
What is the outcome of meiosis? |
• Produces cells with half the number of chromosomes as the parent cell • Daughter cells are genetically different to each other and the parent cell • Four daughter cells produced |
|
|
What happens in a substitution mutation? |
A base is substituted for another |
|
|
What happens during a deletion mutation? |
A base is removed from the base sequence |
|
|
What does the 'degenerate' nature of the genetic code mean? |
Some amino acids can be coded for by more than one DNA triplet |
|
|
Do all substitution mutations result in a different sequence of amino acids being produced? Why? |
• No • Genetic code is degenerate, so some amino acids can be coded for by more than one DNA triplet |
|
|
Do all deletion mutations result in a different protein being produced? Why? |
• Yes • Frame shift • Different amino acids are coded for • Different primary structure produced • Bonds (ionic, hydrogen and disulfide bridges) form in different places • Protein with a different tertiary structure produced |
|
|
What is a mutagenic agent? |
Something that causes an increase in the rate of mutation |
|
|
What does a mutagenic agent do? |
Increases the probability of a mutation occuring |
|
|
Give 2 examples of common mutagent agents |
• UV/ultraviolet light • Ionising radiation |
|
|
What is chromosome non-disjunction? |
A failure of chromosomes to separate properly |
|
|
What is a chromosome mutation? |
Meiosis goes wrong, leading to cells produced containing variations in the numbers of whole chromosomes or parts of chromosomes |
|
|
Give an example of a type of chromosome mutation |
Chromosome non-disjunction |
|
|
Definite genetic diversity |
The number of different alleles of genes in a species or population |
|
|
What does a large number of alleles mean in terms of characteristics and genetic diversity? |
• Large variety of different characteristics • High genetic diversity |
|
|
Name two ways genetic diversity can be increased within a population |
• Mutations in the DNA to form new alleles • Different alleles being introduced to a population by the migration of individuals into it |
|
|
What is a genetic bottleneck? |
An event that causes a big reduction in a population, reducing the number of different alleles in a gene pool and so reducing genetic diversity |
|
|
What is the founder effect? |
A few organisms from a population start their own colony They only have a small number of different alleles in the intial gene pool Low genetic diversity within the end population |
|
|
Describe natural selection |
• Theres a differential reproductive success in a population • Individuals with an allele advantageous to their survival are more likely to survive, reproduce and pass on their genes to their offspring • Great proportion of the next generation inherits the advantageous allele • They are also more likely to survive and reproduce • Frequency of the advantageous allele increases from generation to generation • Over time, this leads to evolution |
|
|
Define evolution |
The gradual change in species over time |
|
|
What are the two key factors of evolution? |
Adaptation and selection |
|
|
What are the three types of adaptation? |
Behavioural Physiological Anatomical |
|
|
What is a behavioural adaptation? |
The way an organism acts to increase its chance of survival or reproduction |
|
|
What is a physiological adaptation? |
The processes inside an organisms body that increase its chance of survival |
|
|
Give two examples of behavioural adaptations |
Playing dead Dancing before mating |
|
|
Give two examples of physiological adaptations |
Low metabolic rate over winter leading to hibernation Production of antibiotics by bacteria |
|
|
What is an anatomical adaptation? |
Structural features of an organisms body that increase its change of survival |
|
|
Give two examples of anatomical adaptations |
Streamlined shape eg fish Layer of blubber or fat to keep them warmer |
|
|
What are the three types of selection? |
Directional Stabilising Disruptive |
|
|
What is directional selection? |
Individuals with alleles for certain characteristics of an extreme type make them more likely to survive and reproduce |
|
|
What might cause directional selection? |
Changes in environment |
|
|
Give an example of directional selection |
Bacteria becoming antibiotic resistant |
|
|
What is stabilising selection? |
The extremes of phenotype ranges are eliminated |
|
|
Give an example of stabilising selection |
Birth weight |
|
|
What about the environment may lead to stabilising selection? |
Constant environment |
|
|
What is disruptive selection? |
Favours extreme phenotypes over intermediate phenotypes |
|
|
What is the least common form of selection? |
Disruptive |
|
|
Which type of selection can lead to one species evolving into two different species? |
Disruptive |
|
|
Give 3 aseptic techniques |
• Disinfect work surfaces before you start working and after youve finished • Work near a Bunsen burner; any microbes in the air will rise with the hot air • Sterilise the wire inoculation loop before and after each use • Flame container necks • Sterilise glassware before and after use |
|
|
What is phylogeny? |
Study of evolutionary history of groups of organisms |
|
|
What is taxonomy? |
The science of classification of organisms |
|
|
What are the three large domains? |
Eukarya Bacteria Archaea |
|
|
What are the 8 taxon groups in order |
Domain Kingdom Phylum Class Order Family Genus Species |
|
|
How does the binomial system work? |
First part = genus Second part = species |
|
|
What is important about the binomial system? |
Internationally accepted |
|
|
What language does the binomial system used for classification of organisms stem from? |
Latin |
|
|
What does giving an organism a scientific name do? |
Standardises the naming system to help prevent confusion between different languages |
|
|
What is courtship behaviour? |
Behaviour carried out to attract a healthy mate of the same species |
|
|
Give 3 examples of simple courtship behaviours |
Releasing chemical Using sound Visual displays |
|
|
Give 2 examples of complex courtshop behaviours |
Dancing Building |
|
|
Why is species specific courtship behaviour important? |
Members of the same species can identify each other Prevents interbreeding More successful reproduction |
|
|
How is courtship behaviour specific? |
Species specific |
|
|
What can courtship behaviour be used for by zoologists? |
Classifying organisms |
|
|
What can genome sequencing be used for? |
Seeing how closely related two individuals are; compare their DNA base sequences |
|
|
What are the main three methods used to clarify evolutionary relationships? |
Comparing DNA base sequences; genome sequencing Comparing amino acid sequences Immunological comparisons |
|
|
Why can immunological comparisons be used to clarify evolutionary relationships? |
Closely related organisms will have similarly shaped proteins that will bind to the same antibodies |
|
|
What is variation? |
The differences that exist between individuals |
|
|
What can variation be caused by? |
Genetics Environmental factors |
|
|
What is the reason for genetic variation within a species? |
Individuals of the same species have the same genes, but different alleles |
|
|
What kind of environmental factors can cause variation? |
Climate Diet Lifestyle |
|
|
Why is random sampling carried out? |
To make sure the sample isnt biased |
|
|
What is standard deviation? |
It tells you the spread of values around the mean |
|
|
How do you calculate standard deviation? |
Square root of [(sum of(X-Y)squared) ÷ (n-1)] Where X = value, Y = mean and n = number of values |
|
|
What is biodiversity? |
The variety of living organisms within an area |
|
|
What is a habitat? |
A place where an organism lives |
|
|
What is a community? |
A habitat inhabited by populations of different species |
|
|
What is species richness? |
Measure of the number of different species in a community |
|
|
What is the index of diversity? |
A method of calculating and measuring biodiversity |
|
|
What is the equation for index of diversity? |
D= [N(N-1)] ÷ [SUM of n(n-1)] N = total number of organisms of all species n = total number of organisms of one species |
|
|
How is DNA stored in a eukaryotic cell? |
• Nucleus • Long double-helix DNA molecule is wound around histones, which support the DNA • DNA and histones are coiled up tightly repeatedly to make a compact chromosome |
|
|
How is DNA stored in prokaryotic cells, mitochondrion and chloroplasts? |
The circular chromosome condenses by supercoiling |
|
|
What is a gene? |
A sequence of DNA bases that codes for a polypeptide or a functional RNA |
|
|
What are functional RNA? |
RNA that perform special tasks during protein synthesis |
|
|
Is mRNA a functional RNA? |
No |
|
|
Name two functional RNA molecules |
Ribosomal RNA (rRNA) tRNA |
|
|
Is tRNA a functional RNA? |
Yes |
|
|
What is a ribosome made up of? |
Protein rRNA |
|
|
What is the genome? |
The complete set of genes |
|
|
What is a proteome? |
The full range of proteins that an organism is able to produce |
|
|
What is a section of non-coding DNA called? |
Intron |
|
|
What is a section of coding DNA? |
Exon |
|
|
What is an intron? |
A section of DNA that doesnt code for a protein |
|
|
What is an exon? |
A section of DNA that codes for a protein |
|
|
Do eukaryotic cells contain introns? |
Yes |
|
|
Do prokartoyic cells contain introns? |
No |
|
|
What is a matching pair of chromosomes called? |
Homologous pair |
|
|
What is a homologous pair of chromosomes? |
A matching pair of chromosomes which both have the same genes, but may have a different set of alleles |
|
|
What is protein synthesis? |
Production of proteins from the sequence of bases in DNA |
|
|
What are the main stages in protein synthesis? |
Transcription Translation |
|
|
Where does transcription take place? |
Nucleus |
|
|
What kind of RNA is produced in transcription? |
mRNA |
|
|
What is mRNA? |
mRNA is made during transcription. It transports the genetic code from the DNA to the ribosomes, where it is used in translation mRNA is a single polynucleotide strand |
|
|
What are three adjacent bases in an mRNA molecule called? |
Codons |
|
|
What is transfer RNA? |
Transports amino acids that are used to make proteins into the ribosomes for translation Single polynucleotide strand folded into a clover shape |
|
|
What is the sequence of three bases on a tRNA molecule called? |
Anticodon |
|
|
Describe transcription |
• DNA helicase unwinds the DNA double helix, breaking hydrogen bonds • RNA polymerase lines up free floating RNA nucleotides alongside the complementary exposed bases on the DNA template • RNA polymerase joins the nucleotides together by phosphodiester bonds • Pre mRNA is formed • As the RNA polymerase moves along the DNA template, the hydrogen bonds between the two DNA strands form again behind it, reforming the DNA double-helix • When RNA polymerase reaches a stop signal it detaches |
|
|
Describe mRNA splicing |
Pre-mRNA is spliced to remove introns and form mature mRNA |
|
|
Does splicing take place in prokaryotes? Why? |
No There are no introns in prokaryotic cells |
|
|
Describe translation |
• mRNA attaches to ribosome • tRNA carry amino acids to the ribosome; ATP provides energy for the bond between amino acid and tRNA molecules • tRNA with anticodon complementary to codon on mRNA join by completemary base pairing • Process repeats • Amino acids join by peptide bonds to form a polypeptide chain • tRNA molecule moves, leaving the amino acid behind |
|
|
How is the genetic code non-overlapping? |
Base triplets dont share their bases |
|
|
How is the genetic code universal? |
The same base triplets code for the same amino acids in all living organisms |
