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31 Cards in this Set
- Front
- Back
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sexual reproduction |
traits are inherited through gametes, offspring express a combination of genes from both parents + is genetically unique |
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asexual reproduction |
barring mutation, offspring of organisms are genetically identical clones of the parent |
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homologous chromosomes |
one set of chromosomes comes from mum, one set comes from dad, 46 altogether |
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binary fission / budding |
forms of asexual reproduction, genetically identical clones |
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gene locus |
position of a gene on a chromosome |
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loci |
multiple gene locations |
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heterozygous |
one of each gene, one different (Aa) |
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homozygous |
AA or aa, two of the same gene |
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gene expression |
can be dominant or recessive |
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alleles |
versions of the same gene that code for a variant of the same polypeptide - may be more than 2 alleles i.e. blood type |
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genotype |
genetic makeup, allele type (Aa, AA or aa) |
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phenotype |
observable features or traits (left handed, brown hair etc) |
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heterozygotes people |
carriers for recessive allele, may be unaware that they carry a recessive allele until they have children |
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punnet square |
the punnett square is used to represent the outcome of crosses; gametes from each parent are separated on each axis and recombined in spaces on the grid |
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autosomal traits |
genes on autosomes, can show complete, incomplete or co-dominance |
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complete dominance |
dominant allele completely covers up the recessive allele |
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co-dominance |
A genetic scenario where neither allele is dominant or recessive and both get expressed |
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multiple alleles |
if there are 3 ore more allele present, it is referred to as a multiple allele system
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ABO blood grouping |
3 alleles (Ia, Ib, i) 6 genotypes (IaIa, Iai, IbIb, Ibi, ii) 4 phenotypes (A, B, AB, O) |
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lethal alleles |
- recessive - a certain combination can kill offspring / decrease chance of offspring survival |
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sex linked traits |
dependedent on the sex of the individual and is directly tied to the sex chromosomes |
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x-linkage |
sex linked genes present on the X chromosome - son will always be affected |
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how to tell if it is a sex linked gene |
- all affected males have carrier or affected mother - son will always be affected or unaffected - all males whose mother is affected will also be affected - males are affected much more than females - all females with affected father or mother are carriers |
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X-inactivation |
sometimes a single characteristic is controlled by the alleles of two or more genes interacting with one another e.g. height, skin colour |
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discontinuous variation |
members of a population can be organised into a few discrete and non-overlapping classes in regards to a trait (e.g. ABO blood grouping) |
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continous variation |
members of a population may vary across a continuum (height, hair colour, skin colour) |
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dihybrid crosses |
inheritance patterns of two traits, genes described are carried on seperate chromosomes and assort independently during meiosis (no linkage) |
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Mendel's law of segregation |
each pair of alleles is sorted into different gametes and subsequently into different offspring gametes contain only one copy of a gene since they only receive one chromosome from each homologous pair |
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law of independent assortment |
- different traits sorted independently - each group of allele is distributed to gametes with equal probability alleles on one pair of homologous chromosomes seperate independently from allele pairs on other chromosomes |
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linked genes |
genes on same chromosome are said to be linked, inherited together as a unit and do not undergo independent assortment |
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crossing over |
during final division of meiosis, the chromatids that were bound together are separated, each of the four chromatids, with any recombined genes, will end up in one of the four gametes |
