Genetics Flashcards
what is genetics
biological branch of study that focuses on the hereditory and variation of organisms
who is known as the father of genetics
gregor mendel
who was gregor mendel
austrian monk who discovered the basics of genetics from cross breeding pea plants
name 3 Mendel’s laws of Genetics
law of segregation, law of dominance, law of independent assortment
explain the law of segregation
it states that for each characteristic, an organism possesses 1 gene consisting of 2 alleles which separate during meiosis so that each gamete only contains 1 allele.
explain the law of dominance
states that when two individuals with pure breeding (homozygous) contrasting characteristics are crossed, the individuals of the F1 generation all display the dominant characteristics.
explain the law of independent assortment
various “factors” controlling the different characteristics (seeds shape, seed colour, plant height, and flower colour) are separate entities, not influencing each other in any way, and sorting themselves out independently during gamete formation.
what is a gene?
length of DNA at a particular location on a chromosome that influences a particular characteristic
what is a allele
alternative form of a gene found at the same location
dominant allele
allele expressed in the phenotype - capital letter
Recessive allele
Allele that’s only expressed in the phenotype if the dominant allele is not present. - lower case
locus
location of a gene on the chromosome
phenotype
external appearance of an organism
genotype
genetic composition of an organism
Homozygous
organism has 2 copies of the same allele for that characteristic
Heterozygous
organism with 2 different variation of the allele for that characterisitic
autosome
a chromosome that is not sex linked.
gonosome
a sex chromosome
genome
entire genetic blueprint of an organism
karyotype
individuals collection of chromosomes
sex linked allele
allele located on the sex chromosome
sex linked disorder
disease determinded by the genes located on the sex chromosome
carrier
heterozygous organism that carrier an allele for a particular disorder without it being expressed.
mutation
sudden unexpected change in the genetic structure of a cell.
mutagen
factor that causes mutations
scientific term for position
locus
what is the difference between homozygous dominant and homozygous recessive
dominant contain both dominant alles, recessive contain both recessive.
what does heterozygous mean
alles that carry different variation of genes.
plural of locus
loci
how are dominant alleles represented
with capital letters
how are recessive alleles represented
by lower case letters
what does the word monohybrid mean
crossing of one characteristic
what are the 2 methods that can be used to determine the offsprings possibility of inheriting various traits
monohybrid crosses, punnet square
name 3 things that are needed before you can draw a punnet square
- characteristics
- phenotype of parents
- genotype of parents
name 3 things that you can determine ater you draw a punnet square
- phenotype of offspring as a %
- phenotype of offspring as a ratio
- genotype of offspring %
name the 3 types of allele dominance
- complete
- co-dominance
- incomplete dominance
what is complete dominance
it’s when a dom allele completeley masks the recessive allele, causes the dominant allele trait to be physically expressed
what is co-dominance
when both alleles are expressed equally in the heterozygous organism. both are equally dominant.
Explain partial dominance
neither allele is dominant, blending of the phenotypes is expressed.
name 2 examples of partial dominance
pink flowers, wavy hair
explain dihybrid cross
crossing of 2 different traits
phenotypic ratio in a dihybrid cross between 2 heterozygous individiaual
9:3:3:1
by what is the bio sex of an organism determined
gonosome
XY
male
XX
female
X is long/short
long
Y is long/short
short
what are sex linked allele
alleles located on the sex chromosomes.
why are most sex linked disorders more common in males
sex linked disorders result from a recessive allele being present on the x chromosome & with the Y chromosome being shorter there is no matching allele for the same gene (no masking)
name 2 examples of sex linked disorders
haemophillia and colour blindness.
what are pedigree charts
diagrams that show occurence and appearance of phenotypes of a particular geneo or organism and its ancestors over several generations. used to show pattern of inheritance and to predict offspring.
what is a mutation
sudden and unexpected change in genetic structure of a cell
name 4 causes of mutations
UV lights
x-ray radiation
radioactive elements
chemicals
name the 3 groups of mutations
useful / harmless / harmful
what are useful mutations
they result in new phenotypes that allow for adaptation to changing environments and natural selection.
what are harmless mutations
cause a physical change in an organism but don’t affect functioning.
occurs in 98% of DNA that doesnt code
name 3 examples of harmless mutations
tongue rolling, blue eyes, red hair
what are harmful mutations
these mutations decrease change of survival of organism.
name 4 examples of harmful organism
down syndrome
CF
haemophilia
turner syndrome
name the 2 types of mutations
point gene mutations
frame shift mutations
what is a point gene mutation
the change in a single base pair at one point.
substituition or inversion
what is frame shift gene mutation
more dangerous
shift in the base pairs on the codon.
causes a change in AA sequence.
addition / deletion / duplication.
name the 5 things that can happen during chromosomal mutations
duplication inversion deletion insertion translocation
explain sickle cell aneia
RBC are sickle shaped rather than bioncave
carry less oxygen
blockages in small blood vessels
explain albinism
group of genetic disorders characterized by the lack of pigment melatin.
explain haemophillia
person lacks the clotting factor.
whta is genetic modification
direct and deliberate modification of an organisms genes and characteristics by biotechnology.
term for the organism recieving the gene
transgenic
explain artificial insulin production
- human insulin gene isolated and removed by restriction enzymes from a healthy human beta cell
- gene is inserted into the plasmid genome of the bacterium with the help of DNA ligase.
- plasmid with recombinant DNA is placed into the bacterium.
- transgenic bacteriym multiply, producing human insulin
- extracted and purified.
advantages of artificial insulin production
rapid
inexpensive
few side effects
what vaccine is produced in a similar way to insulin
Hepatitis B
name the 2 ways that genes are artifically inserted into a plant cell
gene gun
vector like agrobacterium tumefaciens
explain the gene gun process.
required DNA is shot directly into the isolated plant cell.
required DNA coated onto small metal pellets that are loaded into the gene gun.
explain the vector system
gene is inserted into bacterium where it forms recombinantDNA within plasmid .
•
Bacteria under plant & release plasmids intothe plant cells.
bacteria usually enter through damaged tissue of plant.
•
Plasmids become part of the plant’s genetic composition.
•
Tissue sample is extracted & cultivated in a growth medium.
• Gm cells divide & multiply forming a large number of cells.
•
Each cell develops & grows into a new plant w/ desired traits
& characteristics.
uses of GM
medicine production resistant crop formation increased crop yield nutritional value of food increases shelf life improved taste organisms that clean up environment
name 4 reasons why GM is seen as controversial
- unsure of long term side effects
- violation of natural organisn
- loss of biodiversity
- playing god
- expensive
- religious issues
