Genetics (Topic 7A) Flashcards
a gene is…
a section of DNA that is a sequence of nucleotide bases and determines a single characteristic
multiple alleles are…
if more than two alleles for each gene are present in the gene pool
co dominant is when…
both alleles contribute to the phenotype
modification is…
any change to the phenotype. it is not inherited by the future generation
alleles are…
different forms of the same gene
phenotype is…
the physical and observable characteristics of an organism that is determined by an organisms alleles and environment
recessive alleles need to be inherited from _____ _____ to be expressed in the _____
both parents
phenotype
homozygous dominant is…
an organism that has inherited two dominant alleles
homozygous recessive is…
an organism that has inherited to two recessive alleles
heterozygous is when…
an organism that has inherited one dominant and one recessive allele
a mutation is…
any change to the genotype caused by change in DNA and can be inherited
genotype is…
the genetic makeup of an organism
dominant alleles only….
need to inherit one from parents to be expressed in phenotype
incomplete dominance is when…
neither allele is dominant, both are equally giving an intermediate
what are the three blood groups?
A, B and O
which blood groups are dominant?
A and B
which blood group is recessive?
O
sex linkage occurs when…
the genes for a certain characteristic are carried on the sex chromosome
which chromosome is longer X or Y?
X
chromosome __ is longer than __ so it ______more alleles
X
Y
carries
red green colour blindness is caused by a _____ allele
recessive
males only inherit __ allele from their ______
1
mother
are men colourblind if they inherit one allele for colour blindness
yes
is colour blindness more prevalent in men or women?
men
dihybrid crosses investigate….
the inheritance of two characteristics
epistasis is when…
the allele of one gene affects or masks the expression of another in a phenotype
autosomal linkage is…
when two or more genes are located on the same chromosome
autosomal linked genes are more…
likely to be inherited together
the ____ of the loci of the _ genes on the chromosomes the ____ the chance of recombination forming
closer
2
lower
recombinants are…
new combinations of phenotypes that prove linkage is not complete
how are recombinants produced?
crossing over of chromatids
the chi squared test is used to…
test if the observed frequency matches the expected frequency
the null hypothesis states that
there is no statistically significant difference between the observed frequency and the expected frequency
if the value for x^2 exceeds the critical value then…
you reject the null hypothesis
degrees of freedom =
no. of categories - 1
what does 2pq stand for in the hardy-weinberg principle?
heterozygous
the specific point of a gene on the chromosome is called the…
locus
the gene pool is…
all of the alleles present in a population
Why are males more likely to inherit a sex linked recessive condition than females?
2 marks
- males only need to inherit one allele to have the characteristic
- whereas, females need two recessive alleles
A grey body long winged fly is crossed with a black bodied short winged fly. Explain these results:
Grey B + long W - 223
Black B + short W - 218
2 marks
- The genes for colour and wing length are linked
- There is no crossing over
