Patters of Inheritance (4)

Question 1

DNA

Answer 1

• basic genetic material made of nucleic acid DNA
• has 4 nucleotides
• encodes info to make RNA and proteins

Question 2

Genes

Answer 2

• unit of hereditary
• specific trait in the succesive generations of an organism ?

Question 3

Alleles

Answer 3

• alternate forms of a gene
• responsible for a particular trait
• can be exchanged during crossing over and recombination during miosis

Question 4

Locus

Answer 4

• location of a gene or a few genes in a chromosome
• closely located genes within a locus are less likely to be separated during recombination (meiosis)

Question 5

Chromosomes

Answer 5

• have several loci
• ## exist as chromatin during interphase and condense into chromosomes during cell division

Question 6

Genotype

Answer 6

• assorted collection of various genes in the chromosomes

ex.) AA, Ae, bb

Question 7

Phenotype

Answer 7

• refers to a physical trait, condition, or biochemical aspects deterined by the genes
• ex.) eye color, sickle cell anemia

Question 8

Homozygous

Answer 8

organism with a pair of identical alleles for a particular gene in both the homologous chromosomes

ex.) AA, aa, BB, bb

Question 9

Heterozygous

Answer 9

• organism with mixed allele pairs for a particular gene
• an organism can be homozygous for 1 gene and heterozygous for another
• ex.) Cc, Dd

Question 10

Dominant allele

Answer 10

allele of a gene that is expressed under both homozygous and hetrozygous conditions
- Denoted in capital letters (AA, BB, CC)

Question 11

Recessive allele

Answer 11

allele of a gene that is only expressed under homozygous conditions
- denoted by small leters (aa, bb, cc)

Question 12

Recessive allele

Answer 12

allele of a gene that is only expressed under homozygous conditions
- denoted by small leters (aa, bb, cc)

Question 13

Law of segregation

Answer 13

Allele pairs separate during gamete formation and the paired condition is restored by the random fusion of gametes at fertilization

Question 14

Test cross

Answer 14

done by hybradizing a parent with an unknown genotype with a known homozygous recessive parent to find out if the unknown genotype is homozygous or heterozygous

Question 15

Law of independent assortment

Answer 15

the segregation of each allele pair is independent of other allele pairs. the individual allele pairs need to be located on separate loci, far from each other to allow independent assortment during gamete formation

Question 16

Recombinant phenotypes

Answer 16

combinaiton of dominant and recessive phenotypes

Question 17

Intermediate inheritance or incomplete dominance

Answer 17

homozygotes have a particular phenotype and heterozygotes have an intermediate phenotype showing no single gene is completely dominant.

ex.) red flowers (RR) crossed with white (rr) create all pink flowers (Rr)

Question 18

Codominance

Answer 18

both the phenotypes are expressed at about equal levels by the expression of two types of proteins by two alleles

ex.) blood type AB showing proteins for both type A and type B in blood cells

Question 19

Pleiotropy

Answer 19

one gene or allele codes for more than one phenotype
- several symptoms can be traced back to one gene
- individual gene affects many phenotypes
- several genes in a locus responsible for varied effects

Question 20

Epistasis

Answer 20

• one gene interferes with the expression of another gene
• several pairs of alleles may interact to affect a single phenotype

Question 21

Multiple genes

Answer 21

some genes exist in more than two forms

ex.) skin color in humans determined by 3 genes (A, B, C)

Question 22

Sex-linked inheritance

Answer 22

the phenotypes affected by genes located on sex chromosomes are expressed depending on the sex of the individuals
- xx, xy

Question 23

Maternal inheritance

Answer 23

• genes present in mitochondria and chloroplast are always inherited materanally
• only the nuclear genes are carried from on from one gamete to another by the male

Question 24

Environmental effect on gene expression

Answer 24

the interaction of the environment on one gene expression results in wider variation especially in genes controlled by multiple genes

ex.) sunlight can intensify melanin pigmentation