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Aqa a level biology topic 4 summary
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Subject: Biology Topic: Genetic information, variation and relationships Year Group: 12between organisms (1) Key Vocabulary
DNA, genes and chromosomes
1 Prokaryotic cell Unicellular organisms that
Feature Prokaryotic cells Eukaryotic cells internal membrane-bound
have a nucleus, however g
1 Size Small Larger chromosome; a piece of ci
DNA.
2 Uni/multicellular Unicellular Often multicellular
2 Eukaryotic cell Cells that contain a nucleu
3 Organelles No nucleus or Nucleus & membrane bound organelles enclosed by a plasma mem
membrane bound plants and animals.
organelles Full set of DNA found in o
3 Genome
4 DNA shape Circular, without Linear associated with histones to form
Full range of proteins that
histones, free in chromatin, in nucleus 4 Proteasome
genome
cytoplasm Investigating diversity (1)
Short section of DNA that
5 Gene
5 Ribosomes Small (70s) Large (80s) 1 Genetic diversity The greater the number of different hence polypeptides and fun
alleles that all members of a species
6 Cytoskeleton No Yes Thread like structures that
possess, the greater the genetic 6 Chromosome
diversity of that species. tightly coiled around its ass
7 Motility Rigid rotating Flexible waving cilia or flagellae (tubulin) Deoxyribonucleic acids
flagellum (flagellin) 7 DNA
2 Allele frequency The number of times an allele occurs A protein that provides str
8 Cell division Binary fission Mitosis or meiosis within the gene pool in a population, 8 Histones
chromosome. DNA wraps
relative to all others at same locus eukaryotic cells to form nu
9 Reproduction Asexual Asexual or sexual
4 Gene pool All the different alleles of all the compact shape
10 Metabolic Huge variety Common pathways genes of all the individuals in a 9 Chromatid Each of the two thread-lik
pathways population at any one time chromosome divides that
11 DNA in other NA DNA present in chloroplasts & single centromere prior to
4 Comparing genetic Within or between species;
regions mitochondria resembling prokaryotic diversity a) Frequency of Alternative forms of a part
10 Allele
DNA measurable/observable base sequences, and theref
characteristics 11 Triplet Three consecutive nucleot
12 DNA is… Definition
b) Base sequence of DNA one amino acids
a) Non The genetic code is composed of nucleotide triplets. Three c) Base sequence of mRNA
Location of a specific gene
overlapping nucleotides in mRNA (a codon) specify one amino acid in a d) Amino acid sequence of 12 Locus
protein. Each base appears in only one triplet – each base is proteins
only read once. 13 Codon A sequence of three DNA
5 Gene technology Has caused a shift in methods of specific amino acid
b) Degenerate A genetic code in which a single amino acid may be coded for investigating genetic diversity from
by more than one triplet code. solely looking at observable features 14 Nucleosome A structural unit of a euka
consisting of a length of D
c) Universal The genetic code is the same in all living organisms – this is 6 Variation Is caused by genetics (inherited) and histones (approx. 8)
indirect evidence for evolution. environmental factors. Can be
All organisms use DNA to transcribe RNA, and translate that investigated quantitatively within a 15 Chromatin A complex of DNA and pr
species by random sampling. cells. Its primary function i
RNA into proteins. Every living organism uses that same system.
molecules into more comp
, Subject: Biology Topic: Genetic information, variation and relationships Year Group: 12
between organisms (2) Key vocabulary
Biodiversity (see key vocab)
Investigating diversity (2)
1 Biodiversity The variety of organisms in an ar
1 Simpson’s A formula is used to quantify the global scale
SAMPLING METHODS (3 types)
index of biodiversity of a habitat. It takes into
1 Random Sampling a population to eliminate bias. Each member of 2 Species A group of individual organisms
diversity account the number of species present
sampling the population is equally likely to be included. Random physiological and behavioural cha
formula as well as the abundance of each species. members are able to interbreed
sampling with quadrats is used to examine differences
between contrasting habitats within an habitat. 3 Habitat The range of habitats in which di
2 Quadrat In each habitat, mark out a 10m x 10m square on the habitat will be occupied by a ran
technique ground by laying one tape measure 10m lengthways and a 4 Ecosystem A community of living organisms
second tape measure 10m at right angles to the first. nonliving components of their en
Use a random number table or random number system. These biotic and abiotic
generator to select numbers from 1-10. Use pairs of together through nutrient cycles
numbers as x and y co-ordinates. Use the metre interval
markings on each tape measure to locate the lower left 5 Biodiversity The range and variety of genes, s
hand corner of a frame quadrat.Take at least 10 quadrat particular region. Made up of thr
samples in each area. diversity, species diversity and ec
3 Stratified A proportionate number of observations is taken from 6 Species Number of different species and
sampling each part of the population. Divide a habitat into zones diversity each species within any one com
which appear different and take samples from each zone.
7 Species The number of different species
4 Systematic Used where the study area richness community. It does not take acc
sampling includes an environmental species or their relative abundan
gradient. A line transect is
used to sample systematically 8 Variation Differences between individuals.
2 Reducing Farming techniques reduce biodiversity (between different species) or in
along the environmental
biodiversity with methods such as; monoculture, use gradient. Eg: every 10 meters (between individuals of the same
of herbicides & pesticides, hedgerow along a line running from evolution.
removal & woodland clearance seashore inland across 9 Directional Favours one extreme of the rang
a sand dune selection other extreme is selected agains
3 Conserving Conservationists protect biodiversity
5 Sampling bias When a sample is collected in such a way that some 10 Stabilising Favours the mean of the distribu
biodiversity with methods such as; giving endangered members of the intended population are more or less selection are at a selective disadvantage –
species legal protection, creating likely to be included than others. The data you collect phenotype increases
protected areas & the environmental may therefore not be accurate or represent the group.
stewardship scheme. A balance between 11 Polygenes Group of genes that are respons
6 Sample size The number of observations in a sample. characteristic.
conservation & agriculture is needed
7 Mean A type of average where you add up all of the numbers 12 Normal A bell-shaped curve produced w
10 Quadrat A frame, traditionally square, then divide by how many numbers there are. distribution plotted on a graph
used in ecology to isolate a curve
standard unit of area for 8 Median A type of average where you place the numbers you are
study of the distribution of given in value order and find the middle number. 13 Ecosystem Range of different habitats within
an item over a large area. diversity
9 Mode Type of average , the number that occurs the most often.
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