GENETICS EXAM QUESTIONS Flashcards
SEX LINKAGE
a gene located on a sex chromosome
CO-DOMINANT
paris of alleles that both affect the phenotype when present in a heterozygote
RECESSIVE
an allele that produces its characteristic phenotype only when present in homozygous state
LOCUS
the specific position of a gene on a chromosome
EXPLAIN HOW MALES INHERIT HEMOPHILIA AND HOW FEMALES CAN BECOME CARRIERS FOR THE CONDITION
hemophilia is due to a recessive allele
sex linked disease
X chromosome
H^h
males have XY
females have XX
males can only inherit hemophilia from their mothers and cannot pass it on to their sons
men have a 50% chance of inheriting hemophilia if their mother is a carrier
punnett grid
males only have one X chromosome so if it carries the allele for hemophilia then it is expressed as there is no other X chromosome to mask it
females can be carriers
and they can inherit the trait from either parent
OUTLINE THE USE OF NAMED ENZYMES IN GENE TRANSFER OF USING PLASMIDS
plasmids are removed/ obtained from bacteria
endonuclease/ restriction enzymes cut the plasmids at target sequences
DNA fragments of other orgs are cut the same the restriction enzymes
in both DNA and plasmids, complementary sticky ends are produced
DNA segment added to opened plasmid
stuck together by lipase
reverse transcriptase makes DNA copies of mRNA/ DNA polymerase to increase amount of DNA
recombinant plasmid enters into new host cells
cultured/ cloned to produce new gene
DISCUSS THE BENEFITS AND POSSIBLE HARMFUL EFFECTS OF ALTERING SPECIES BY ONE EXAMPLE OF GENETIC MODIFICATION
DNA is universal
gene modification is the transfer of genetic material between species
e. g glyphosate resistant crop
source: bacteria
function of gene: resistance to herbicides
modified org: soya beans
:) increase crop yield
:) reduction in use of herbicides
:( could be transferred to wild plants
:( cause cancer/allergies in the future
DESCRIBE THE APPLICATION OF DNA PROFILING TO DETERMINE PATERNITY INVESTIGATIONS
DNA from child, mother and possible father used
legal reasons/ divorce/ inheritance
for personal reasons
samples of DNA are amplified/ fragments separated by electrophoresis
pattern of bands of DNA is produced in a gel
analysed for matches between child and mother and possible father
half the child bands will match the father while the other half will match the mother
EXPLAIN THE INHERITANCE OF COLOUR BLINDNESS
colour blindness is caused by recessive alleles
gene located on X chromosome/sex linked
x^b is recessive allele for colour blindness AND x^B is allele for normal colour
male has one X and Y chromosome
male has only one copy of each gene located on x chromosome
X chromosome in males comes from female parent
any male receiving allele from mother will express the trait
X^bY is genotype for colour blind males
many more males have colour blindness than females
female will express colour blindness only if homozygous recessive/ X^bX^b
heterozygous /X^BX^b female will be a carrier
MEIOSIS IN HUMANS PRODUCES CELLS THAT PARTICIPATE IN FERTILIZATION. OUTLINE THE PROCESSES INVOLVED IN MEIOSIS.
meiosis reduces a diploid cell into 4 haploid cells
during P1 homologous chromosomes pair up
chromatids break and cross over
M1 homo chromo at the equator of the spindle
A1 homo chromo seperate and move to opposite poles
T1 chromo reach poles and unwind
P2 chromosomes condense and become visisble, new spindle form
M2 chromo line up at the centre of equator
A2 sister chromatids seperate
T2 chromatids reach the poles and unwind
FOLLOWING FERTILIZATION, CELLS IN THE DEVELOPING EMBRYO DIFFERENTIATE. OUTLINE A TECHNIQUE FOR CLONING USING DIFFERENTIATED ANIMAL CELLS.
somatic cell is taken from donor animal
nucleus from donor cell removed
eggs cells removed from donor animal
nucleus removed from eggs
nucleus if fused with eggs
embryo formed is implanted in uterus of surrogate mother
normal pregnancy and birth is completed
offspring is a genetic copy/clone of the mother nucleus
