Unit 2 exam Flashcards
what are genes
sequences of bases located on chromosomes that code for specific proteins (ATCG)
what do proteins from genes control
traits or characteristics of the organism
what are alleles
different forms of a particular gene
what is an example of a gene and a kind of allele
a gene would be eye colour and an allele of that gene is to have blue eyes
what is a genome
the complete set of genetic instructions for an organism (the total DNA)
how is a genome expressed
as the base sequence of the haploid set of chromosomes
how many chromosomes in a human
46, 23 pairs
how many autosomes in a human
44, 22 pairs
how many sex chromosomes in a human
2
Where do your 46 chromosomes come from
23 from father, 23 from mother
What are homologous chromosomes
matching pairs of chromosomes that have the same genes in the same places (same size)
what is the loci
the position of the gene on a chromosome
what is non-homologous
non-matching chromosomes
what are the 2 types of chromosomes
sex chromosomes and autosomes
how can autosomes be distinguished
the size, position of centromere and patterns of light and dark bands when stained
what is a karyotype
an image of chromosomes from a cell arranged in an organised manner
What do karyotypes do
allow us to see all the chromosomes and see if there is a wrong amount (diseases)
What are the 3 chromosome abnormalities
changes in the number of chromosomes, changes in a part of a chromosome, changed arrangements of chromosomes
what is trisomy
when an organism has an extra in a pair of chromosomes
what it monosomy
when an organism has one chromosome in a pair
what is a genotype
the combination of the particular alleles of a gene or genes that are present and active in a cell or in an organism
what is a homozygous genotype
when a particular gene comprises of two identical alleles, eg AA or aa
what is a heterozygous genotype
when a particular gene comprises of two different alleles, eg Aa
what is a phenotype
A phenotype is the observable or measurable characteristics of an organism. It is a product of the genotype and the environment.
what does codominance mean
when a heterozygote expresses both the dominant and the recessive trait of a gene in its phenotype
what does codominance normally entail
showing both phenotypes or both colours (not mixed)
what is incomplete dominance
appearance in a heterozygote of a trait that is between either of the trait’s homozygous phenotypes
what does incomplete dominance entail
merging of phenotypes or colours together
what are the factors of an autosomal dominant trait (3)
both sexes are featured, all affected people have at least one affected parent, cant reappear after having 2 non affected people
what are the factors of autosomal recessive traits (3)
trait can skip generations, parents that are not affected can have affected kids, if both parents are affected then all children will be as well,
what are some features of X-linked dominant traits (3)
a male with the trait only passes it to all daughters, it disappears if no one is affected, in large pedigrees more females are affected
what are some features of x-linked recessive traits (3)
affected mothers have affected sons, daughters of affected fathers are carriers, across a large pedigree more males will be affected
what is meiosis
sexual reproduction which halves the chromosome number to produce gametes
what are the stages of meiosis
PMAT i PMAT ii
what happens in interphase of meiosis
the DNA is replicated forming 4 chromosomes
what happens in prophase i
the chromosomes condense and nuclear envelope degrades, starting crossing over
what is crossing over (prophase i)
the chromosomes get tangled up and change/combine certain alleles that are random to cause genetic variation
what happens in metaphase i
the new crossed over chromosomes line up down the equator of the cell
what happens in anaphase i
the 4 chromosomes are separated by from each other when the spindle fibres pull them apart via the centromere
what happens in telophase i
a nuclear envelope reforms around each new set of chromosomes (then cytokinesis occurs)
what happens in prophase ii
chromosomes may re-condense again and the nuclear envelope breaks down again
what happens in metaphase ii
the chromosomes line up down the equator of the cell
what happens in anaphase ii
the chromosomes are spilt apart into single stranded ones by pulling from the spindle fibres on the sister chromatids
what happens at telophase ii
a new envelope forms around each set of chromosomes
at the end of meiosis how many haploid daughter cells are made
4 haploid daughter cells are made
what are the causes of genetic variation
crossing over (prophase i) and independent assortment
what is independent assortment
the formation of random chromosome combinations during meiosis that contributes towards producing variation
what are 3 advantages of asexual reproduction?
can reproduce quickly, no energy used to find a mate, and able to colonise areas quickly
what are 3 disadvantages of asexual reproduction?
if conditions change entire population can be lost, no genetic diversity, and pressure on availability of resources
what are 3 advantages of sexual reproduction?
gives genetic diversity, variation means increased survival changes if conditions change, and variation between members of the same family due to crossing over and independent assortment during meiosis
what are the 2 types of cloning techniques?
embryo splitting and somatic nuclear cell transfer
what is embryo splitting?
process of separating the totipotent cells of a very early embryo, so that the resultant cells are each able to form a complete embryo
what is somatic nuclear transfer?
a cloning technique that involves the nucleus of a somatic cell being transferred into the cytoplasm of an enucleated cell that is then stimulated to divide
4
why is genetic diversity so important in a population?
- increases species survival following environmental change
- increases the number of individuals that can survive and reproduce
- increases biodiversity in ecosystems
- means natural selection can act, as there are many alleles to select from.
what are abiotic factors?
Factors affecting a population that are environmental factors
what are 3 examples of abiotic factors?
temperature, dessication (drying out) and weather
what are biotic factors?
factors affecting a population that is a living factor
What are 2 examples of biotic factors?
predators and diseases
what are producers?
A members of an ecosystem community that bring energy from an external source into the ecosystem
what are the main producers?
plants
what is another name for producers?
autotrophic
what is another name for consumers?
heterotrophs
what are consumers?
organisms that obtain their energy and organic matter by eating or ingesting the organic matter of other organisms
what are the 4 subcategories of consumers/heterotrophs?
herbivores, carnivores, omnivores and detritivores
what are detritivores?
which eat decomposing organic matter such as rotting leaves, dung or decaying animal remains
what are decomposers?
organisms, such as fungi, that can break down and absorb the organic matter of dead organisms or their products
what is an example of detritivores?
earthworms
what is the difference between decomposers and detritivores?
decomposers first break down the organic matter outside their bodies by releasing enzymes, and then they absorb some of the products, whereas detritivores don’t
what are the levels of the food chain?
- energy
- producer
- primary consumer
- secondary consumer
- tertiary consumer
what are trophic levels?
a different name for the levels of the food chain
what are keystone species?
species whose presence in an ecosystem is essential for the maintenance of that ecosystem
what is a behavioural adaptation?
Activities that an organism performs in response to internal and external stimuli
what is a structural adaptation?
Physical features of an organism that enable them to survive in a given environment
what is a physiological adaptation?
Internal and/or cellular features of an organism that enable them to survive in a given environment
what is an intraspecific relationship?
Competition for resources between members of the same species
what is an interspecific relationship?
competition for resources between members of different species
what is an amensalism relationship?
one organism is inhibited or destroyed, the other is unaffected
what is a predator-prey relationship?
one species kills and eats the other
what is an herbivore-plant relationship?
an animal eats a plant
what is a parasitism relationship?
an organism living on or within another organism to derive a benefit, whilst harming the host
what is a mutualism relationship?
a beneficial relationship between two species
what is a commensalism relationship?
one member gains a benefit and the other is unaffected
what is symbiosis?
competition for resources in an ecosystem involving members of the same species
what are the 8 types of relationships?
intraspecific, interspecific, amensalism, predator-prey, herbivore-plant, parasitism, mutualism and commensalism
what are the 5 bioethical concepts?
integrity, justice, Beneficence, non-maleficence and respect
what is integrity?
doing the right thing even if no one is looking
what is justice?
equal distribution of benefits, rights, costs, and resources
what is beneficence?
aiming to improve conditions for others through generosity and kindness
what is non-maleficence?
avioding actions which led to harmful consequences
what is respect?
considering the wellbeing, freedom, independence, values and beliefs of all people
