Genetics

Question 1

History of genetics (father?)

Answer 1

Gregor Mendel- Pure breed Pea plants, investigated height, shape colour
tall and short homozygous breed
F1 all tall
F2 one short and 3 tall
Discovery of dominant and recessive genes

Question 2

What does inheritance result to?

Answer 2

differences and similarities between offspring and parent

Question 3

Define chromosomes

Answer 3

long thread like dna strands wond up around histones

Question 4

define chromatin

Answer 4

network of threadlike structures made up of chromosomal material such as DNA RNA and histone proteins

Question 5

define genome

Answer 5

complete set of genetic instructions (genes) required to create an organism

Question 6

Define genes

Answer 6

sections of dna that code for heridaty characteristics

Question 7

How are cells given their character?

Answer 7

different genes are activated to produce specific proteins

Question 8

Define alleles

Answer 8

variations of a gene, different versions of the same gene at the same locus in a homologous chromosome

Question 9

Meiosis/ fertilization in terms of alleles?

Answer 9

Meiosis sperates homologous chromosomes so one allele of each gene pair is present in the gamete
fertilization creates a zygote with on allele from each parent to create pair of alleles

Question 10

Mendels law of segregation?

Answer 10

states that the characteristics of an organism are controlled by pairs of alleles which separate into different gametes during meiosis. one allele of each gene pair will be present in the gamete.

Question 11

Genotype Vs Phenotype?

Answer 11

genotype is genetic make up of an organism
phenotype is physical appearance of an organism (also environment)

Question 12

Dominant allele Vs recessive allele?

Answer 12

Dominant allele is expressed in phenotype while recessive allele supressed in the presense of a dominant allele and not expressed unless dominant allele is not present

Question 13

Mendels law of dominance?

Answer 13

states that in a cross between two parents that are pure for contrasting traits. only the dominant trait will be expressed in the phenotype of the offspring. recessive allele will always be masked by dominant allele

Question 14

Homozygous vs Heterozygous?

Answer 14

homozygous is pair of alleles at a locus are the same for a characterisitic
heterozygous is pair of alleles at a locus are the different for a characterisitic

Question 15

What does a genetic diagram show and give format

Answer 15

shows genotype and phenotype in a cross between parents

Charceteristic
key
P1 Phenotype genotype
meiosis
Gametes:
Fertlization
Punnet Sqaure
F1: Genotype Phenotype
Ratio

Question 16

What is a monohybrid cross?

Answer 16

cross between two parents with different alleles for a single gene

Question 17

3 types of dominance and explain?

Answer 17

complete- dominant expressed and recessive supressed in heterozygous
incomplete- Cross will result in an intermediate phenotye (blend)
co dominance- Both Traits expressed fully and equally in the phenotype

Question 18

How to use test crosses?

Answer 18

Organism has a dominat charcteristic
cross with a homozygous recessive organism
if any of the offspring show the recessive triat then organism was heterozygous

Question 19

Which sex chromosome is longer Male vs female genotypes?

Answer 19

X chromosome longer
Y chromosome shorter and comes from father
XY male and XX female

Question 20

Why does a male embryo develop?

Answer 20

The Y chromosome from the sperm cell has gene cose for gonad tissue which develops into testis to form male whereas females will develop ovaries

Question 21

Why do sex linked disorders affect males?

Answer 21

The mutation occurs on the part of the X chromosome that does not have a homologous pair and as males only have one X Chromosome from mother they cannot carry the normal allele so the recessive mutated allele is expressed

Question 22

Explain Heamophilia?

Answer 22

Disorder which causes excessive frequent bleeding and blood cannot clot correctly as a result of a mutation on the part of the X chromosome which codes for blood clotting from mother

Question 23

Explain red green colour blindness

Answer 23

Mutation on the gene that codes for photopigments to see red and green colours on X chromosome, confusion of red and green hues and affects more males and they only have one X chromosome

Question 24

What are multiple alleles?

Answer 24

more than two alleles for a particular gene characteristic ( one person will only have two alleles for any charcateristic)

Question 25

Alleles of blood groups (antigens?)

Answer 25

A IAIA IAi
B IBIB IBi
AB IAIB
O ii

Question 26

complete/ vs co dominance in blood groupings?

Answer 26

complete dominance is the production of either IA or IB as result of recessive ii present

co dominance is production of antigen A and B in group AB

Question 27

When do blood transfusions work or not?

Answer 27

donor blood group matches recipient means antibodies will not be produced and blood will be accepted

when blood group does not match, the recipient will produce antibodies in WBCs to destroy RBCs which form clumps and block arteries causing death

Question 28

what is a dihybrid cross?

Answer 28

cross between parents who’s alleles for to different genes differ.

Question 29

What do genetic lineages refer to and define pedigree and family tree?

Answer 29

genetic lineages refer to the way that alleles are passed on through several generations

Pedigree diagram are a genetic representation of a family tree showing the inheritance of traits of diseases down several generations

family tree show the genotype and phenotypes through several generations of family

Question 30

mendels law of independent assortment

Answer 30

different allele pair separate independently of each other during the formation of gametes. charctaristics are therefore transimitted to offspring independently of each other.