3.4 Genetic information, variation and relationships between organisms | COMPLETE Flashcards
3.4.1
what is DNA like in prokaryotic cells?
(three)
short
circular
not associated with proteins
3.4.1
what is DNA like in eukaryotic cells?
(three)
very long
linear
associated with proteins (called histones)
3.4.1
what does a DNA molecule and its associated protein make?
a chromosome
3.4.1
which organelles (other than the nucleus) in eukaryotic cells contains DNA and what is it like?
mitochondria and chloroplasts
short
circular
not associated with proteins
3.4.1
what is a gene?
a base sequence of DNA that codes for the amino acid sequence of a polypeptide and a functional RNA
3.4.1
what is a locus?
A gene occupies a fixed position on a particular
DNA molecule
3.4.1
what is a triplet?
a sequence of three DNA bases
3.4.1
what does a triplet do?
codes for a specific amino acid
3.4.1
TRUE OR FALSE
the genetic code is universal, non-overlapping and degenerate
TRUE
3.4.1
TRUE OR FASLE
in eukaryotes, much of the nuclear DNA DOES code for polypeptides
FALSE
in eukaryotes, much of the nuclear DNA does NOT code for
polypeptides
3.4.1
what is an exon?
sections of coding DNA
3.4.1
what is an intron?
non-coding section of DNA
3.4.2
what is the concept of the genome?
the complete set of genes in a cell and of the proteome as the full range of proteins that a cell is able to produce
3.4.2
what is the structure of mRNA?
mostly single stranded and linear in shape
3.4.2
what is the structure of tRNA?
clover leaf in shape
3.4.2
what is the structure of rRNA?
three dimensional in apperance and spherical in shape
3.4.2
are codons and/or anticodons present in mRNA?
only codons
3.4.2
are codons and/or anticodons present in tRNA?
only anticodons
3.4.2
are codons and/or anticodons present in rRNA?
neither are present
3.4.2
what does mRNA do?
carries a fraction of the DNA code to different parts of the cell so it can be translated
3.4.2
what does tRNA do?
small in size and responsible for transferring amino acids from the cytoplasm to a ribosome
3.4.2
what does rRNA do?
it forms the ribosomes and serves as the structure of translation
3.4.3
what type of cell division creates gametes?
meiosis
3.4.3
what are the stages of meiosis in order?
interphase
prophase 1
metaphase1
anaphase 1
telophase1
prophase 2
metaphase 2
anaphase 2
telophase 2
3.4.3
what happens in prophase one?
same as mitosis with the chromosomes condensing nucleus dissolving
3.4.3
what happens in metaphase one?
the homologous chromosomes lined up in pairs at the equator of the cell and spindle fibres form
3.4.3
what happens in anaphase one?
the homologous pairs separate and go to the poles of the cell
3.4.3
what happens in telophase one?
the nuclear membrane reappears and is followed by cytokinesis, two daughter cells occur
3.4.3
what happens in prophase two?
chromatids condenses to form visible chromosomes again
nuclear envelope dissolves
3.4.3
what happens in metaphase two?
spindle fibres connect to the centromere of each sister chromatid
3.4.3
what happens in anaphase two?
spindle fibres pull one sister chromatid to each pole
3.4.3
what happens in telophase two?
the sister chromosomes have reached opposing poles
the spindle disintegrates
a nuclear envelope forms around each haploid chromosome set, before cytokinesis occurs
3.4.3
what are the two ways meiosis creates genetic diversity?
crossing over
independent segregation
3.4.3
what is crossing over?
a cellular process that happens during meiosis when chromosomes of the same type are lined up. When two chromosomes — one from the mother and one from the father — line up, parts of the chromosome can be switched. The two chromosomes contain the same genes, but may have different forms of the genes.
3.4.3
what is independent segregation?
When cells divide during meiosis, homologous chromosomes are randomly distributed to daughter cells, and different chromosomes segregate independently of each other.
This called is called independent assortment. It results in gametes that have unique combinations of chromosomes
3.4.3
what is the equation for the number of different genome types?
(2^n)^2
n = number of chromosome pairs (23 for humans)
3.4.4
how does natural selection and meiosis link together?
Random mutation can result in new alleles of
a gene.
Many mutations are harmful but, in certain environments, the new allele of a gene might benefit its possessor, leading to increased reproductive success.
The advantageous allele is inherited by members of the next generation.
As a result, over many generations, the new allele increases in frequency in the population
3.4.4
define gene
The base sequence of DNA that codes for either the amino acid sequence of a polypeptide OR a functional RNA.
3.4.4
define allele
Alternative/different version of a gene.
3.4.4
define genetic mutation
Change in the base sequence of chromosomes/DNA.
3.4.4
define species
A group of organisms that can interbreed to produce fertile offspring.
3.4.4
define population
The number of organisms of one species that occupy the same habitat at the same time.
3.4.4
define habitat
The place an organism normally lives.
3.4.4
define gene pool
All of the alleles of all the genes that are present in the population at a given time.
3.4.4
define allele frequency
How often a particular allele occurs in a population.
3.4.4
define genetic diversity
Number of different of alleles genes in a population.
3.4.4
define evolution
Change in the allele frequency in a population over time.
3.4.4
define natural selection
The process by which the allele frequency of an advantageous allele increases within a population over time.
3.4.4
how do mutations start evolution?
Random mutation can result in new alleles of a gene.
Many mutations are harmful but, in certain environments, the
new allele of a gene might benefit its possessor, leading to
increased reproductive success.
The advantageous allele is inherited by members of the next
generation.
As a result, over many generations, the new allele increases
in frequency in the population.
3.4.4
what causes low genetic diversity?
very small populations
populations where a lot of inbreeding occurs
mass death
3.4.4
how does death result in a genetic bottle neck?
the original population has many DIFFERENT alleles (e.g. 7)
large number of the population die
the reduced population has lost some of the original alleles
— reproduction —
the new population has a greatly reduced genetic diversity - a genetic bottle neck
3.4.4
what is the Founder effect?
when a small group split off the original population and become genetically isolated
3.4.4
explain how the Founder effect results in low genetic diversity
a small group splits from the original population and forms a new population
they only take a few alleles with them
— reproduction —
in the new population genetic diversity is very low and the allele frequency is increased
the original population maintains a high level of genetic diversity
3.4.4
give examples of selection pressures
Predation
Competition for resources
Diseases
Resistant to drugs/chemicals/medicines e.g. antibiotics, pesticides, herbicides, pollutants.
3.4.4
what are the two types of natural selection?
stabilising and directional
3.4.4
what is stabilising selection?
Individuals with phenotypes towards the middle of the range are more likely to survive and reproduce as they have the selective advantage.
Occurs when the environment isn’t changing and is stable.
3.4.4
what is the result of stabilising selection?
the evolved population has a decreased range and a higher mean compared to the original population
3.4.4
what is directional selection?
Individuals with alleles for one of the extreme phenotypes are more likely to survive and reproduce as they have the selective advantage.
Occurs in response to environmental change
3.4.4
what is the result of directional selection?
the mean shifts to one of the extremes and the range remains the same
3.4.4
what are the three types of adaptions?
behavioural
physiological
anatomical
3.4.4
what are behavioural adaptions?
The way an organism acts, either inherited (innate)
e.g. avoiding light, building webs or learned through experience and observation
e.g. use of tools, language
3.4.4
what are physiological adaptations?
A process that goes on inside an organism
e.g. slower metabolic rate when they hibernate
3.4.4
what are anatomical adaptations?
An internal or external physical feature (part of the organism’s anatomy).
3.4.4
a frog has camouflage to blend into the environment
what time of adaptation would this be?
anatomical
3.4.4
a plant undergoes thigmotropism (directional growth movement for touch stimulus)
what type of adaptation would this be?
behavourial
3.4.4
snakes produce venom to capture prey
what type of adaptation would this be?
physiological
3.4.5
what did Carl Linnaeus develop?
he developed the first classification system
he developed a binomial (two name) system
3.4.5
how do you write a binominal name?
capitalised genus name
lower case species name
italicised when typed or underlined
3.4.5
why are binominal names important?
they allow us to see which animals are closely related/ or not
they also are universal so scientists don’t get confused with different species with the same name
3.4.5
what is courtship behaviour?
the different behaviours that animals demonstrate to attract a mate
3.4.5
why is courtship behaviour important?
help with successful reproduction which helps a whole species survive over time
It will help them pass on advantageous alleles (natural selection) to the next generation and increase the species chance as a whole of surviving
courtship behaviour also increases the likelihood of successful mating, as it enables individuals to recognise members of the same species
3.4.5
give examples of types of courtship behaviours
(five)
releasing a chemical
using sound
colour/visual displays
dancing
building a nest/shelters
3.4.5
how does courtship behaviour increase chance of survival?
Animals will only display courtship behaviours when they are sexually mature and fertile.
This helps to synchronise mating behaviour so that the animals are more likely to mate when the female is releasing eggs so she will be receptive to courtship behaviour from the male.
3.4.5
TRUE OR FALSE
Courtship behaviour can also result in INCREASED survival of the offspring.
This is because the ritual will help form a pair bond between the parents, so they may be MORE likely to stay together and raise the offspring as a team.
TRUE
3.4.5
list the binominal naming system hierarchy
domain
kingdom
phylum
class
order
family
genus
species
3.4.5
what is phylogenetic?
the study of the evolutionary history of groups of organisms, to determine how closely related they are to one another
3.4.6
define biodiversity
the number and variety of living organisms in a particular area at a particular time
3.4.6
what are the types of diveristy?
community/ecosystem
species
genetic
3.4.6
define species diversity
the number of different species and the number of individuals of each species within any one community
3.4.6
define genetic diversity
the number of different alleles of genes in a population
3.4.6
define ecosystem diversity
the range of different habitats, from a small local habitat to the whole of the Earth
3.4.6
list the different habitats on earth
(seven)
temperate forest
tropical rainforest
deserts
grasslands
tundra
chaparral
ocean
3.4.6
what are the two ways we measure biodiversity?
species richness
index of diversity
3.4.6
define species richness
a measure of the number of different species in a community
3.4.6
define index of diversity
describes the relationship between the number of species in a community and the number of individuals in each species
3.4.6
why is index of diversity more useful?
Measures number of individuals of each species and number of species
Some species only present in small numbers
3.4.6
TRUE OR FALSE
A community dominated by one or two species is considered to have a HIGHER biodiversity than one in which several different species have a similar abundance
FALSE
A community dominated by one or two species is considered to have a LOWER biodiversity than one in which several different species have a similar abundance
3.4.6
what is the index of diversity equation?
d = N(N − 1) / Σn(n − 1)
n = total number of organisms of each species
N = total number of organisms of all species
3.4.7
when an organism evolves, does the phenotypes and molecules change or only the phenotype?
their phenotype that changes, but also the molecules from which they are made
3.4.7
how do antigens show how closely related organisms are?
Antibodies are a complementary shape to specific antigens on proteins.
If the proteins are similar between species they will have more of the same antigens on their proteins.
If proteins are similar, the mRNA must be similar so the DNA must also be similar= more closely related.
3.4.7
what are the ways of measuring genetic diversity between species?
the frequency of measurable or observable characteristics
the base sequence of DNA
the base sequence of mRNA
the amino acid sequence of the proteins encoded by DNA and mRNA
