Chapter 14.1 Mendel used the scientific approach to identify the 2 laws of inheritance and 14.2 The Laws of probability govern mendelian inheritance

Question 1

The explanation of heredity most widely in favour in the 1800s was

Answer 1

The “Blending” Hypothesis, the idea that genetic material contributed by two parents mixes in a manner analogous to the way blue and yellow paints

Question 2

Give an example why the blending hypothesis fails.

Answer 2

1. it fails to explain traits reappearing after skipping a generation
2. The results of breeding experiments with animals and plants
3. Everyday observation

Question 3

An alternative to to the “blending” hypothesis

Answer 3

The “gene idea”: a particulate hypothesis of inheritance

Question 4

The “gene idea”

Answer 4

According to this model parents pass on a discrete heritable units- genes- that retain their seperate identities in offspring
. It is more like a deck of cards that are shuffled than a can of paint that gets diluted

Question 5

The father of Modern genetics

Answer 5

Gregor Mendel : documented a paritculate mechanism for inheritance

Question 6

The reason Mendel chose to work with peas

Answer 6

. The had many varieties
. short generation time
. large number of offspring from each mating
. He could strictly control mating between plants

Question 7

CHARACTER

Answer 7

A heritable feature that varies among individuals, such as flower color

Question 8

TRAIT/ Allele

Answer 8

Each variant for a character, such as purple, or white color for flowers

Question 9

Reproductive organs of a plant

Answer 9

Stamens: pollen producing (sperm)
Carpel: egg bearing

Question 10

How did Mendel achieve cross fertilization

Answer 10

. Removed the immature stamen

. then dusted pollen from another plant onto the altered flower

Question 11

What characters of the pea did Mendel track that allowed him to to discover the particulate nature of inheritance

Answer 11

Mendel chose to track only those factors that occurred in 2 distinct, alternative forms ( peas only came in 2 colors purple or white flowers)…. not characters found in continuum like weight
. Used true breeding plants

Question 12

TRUE BREEDING

Answer 12

Plants, over many generations of self pollination had only produced the same variety as the parent plant. ( purple flower parents only produced purple flower offsprings in successive generations

Question 13

HYBRIDIZATION

Answer 13

The crossing of two true breeding varieties F1 would be a hytereozygote

Question 14

P GENERATION

Answer 14

( parental generation) the true breeding parents( of 2 separate varieties)

Question 15

F1 GENERATION

Answer 15

. the first “ filial” generation

The hybrid offspring of the true breeding P-generation

Question 16

F2 GENERATION

Answer 16

. 2nd filial generation

The offspring of F1 generation ( 2 hybrids either self pollinating or cross fertilizing)

Question 17

2 Mendels Law

Answer 17

1. THE LAW OF SEGREGATION

2. THE LAW OF INDEPENDENT ASSORTMENT

Question 18

DOMINANCE VS RECESSIVE traits

Answer 18

Recessive trait :heritable factors for a particular trait that is hidden or masked when a dominant heritable factor is present.

DOMINANT ALLELE: determines the organism’s appearance

RECESSIVE ALLELE : has no noticeable effect on the organism’s appearance

Question 19

“heritable factor”

Answer 19

gene

Question 20

What is the inheritance ratio of F2 generations ( the pattern Mendel observed) ( offsprings of hybrid)

Answer 20

3:1 ( 3 dominant : 1 recessive)

Question 21

What are the 4 concepts that make up Mendel’s Model

Answer 21

1. Alternative versions of genes ( Alleles) account for variations in inherited characters
2. For each character, an organism inherits an organism inherits 2 copies of a gene, one from each parent ( these are also called alleles of that gene.) The may be identical or differ
3. If the 2 alleles at a locus differ, then one , the DOMINANT ALLELE, determines the organism’s appearance ; the other , the RECESSIVE ALLELE has no noticeable effect on the organism’s appearance.
4. The Law of Segregation

Question 22

ALLELE

Answer 22

Alternate versions of a gene. the Dna at a specific locus ( for flower color) vary slight in nucleotide sequence and hence its information content

Question 23

GENE

Answer 23

Is a sequence of nucleotides at a specific place, or locus, along a particular chromosome

Question 24

THE LAW OF SEGREGATION

Answer 24

States that the 2 alleles for a heritable character segregates ( separate from each other) during gamete formation and end up in different gametes.
( Thus an egg or a sperm gets only one of the two alleles that are present in the somatic cells of the organism making the gamete.)

Question 25

If an organism has identical alleles for a particular what occurs in their offspring

Answer 25

Then that allele is present in all gametes. ( The organism is true breeding for that character

Question 26

If different alleles are present what occurs to their offspring

Answer 26

50% of the gametes receive the dominant allele

50% of the gametes receive the recessive

Question 27

PUNNETT SQUARE

Answer 27

a diagrammatic device for predicting the allele composition of offspring from a cross between individuals of known genetic makeup

Question 28

HOMOZYGOUS

Answer 28

An organism that has a pair of IDENTICAL alleles for a character is said to be homozygous for the gene controlling that character.

. They breed true because all their gametes contain the same allele ( PP or pp)

Question 29

Crossing an homozygote dominant and a homozygote recessive

Answer 29

Each offspring will have a dominant and a recessive allele

Question 30

HETEROZYGOTE

Answer 30

An organism that has 2 DIFFERENT alleles for a gene is said to be heterozygote for that gene.

Question 31

PHENOTYPE

Answer 31

An organisms,physiological trait, appearance or observable traits( not only appearance e.g blood type, sex, disease)

Question 32

GENOTYPE

Answer 32

is an organisms genetic makeup

Question 33

TESTCROSS

Answer 33

Breeding an organism of unknown genotype with a recessive homozygote

Question 34

How does a testcross work

Answer 34

If a plant has a purple flower ( Purple being dominant and white recessive) its possible genotypes are homozygous PP or heterozygous Pp.If it is crossed with a homozygous recessive pp
(white) and all the gametes are Pp purple that means the plant is PP or if half are purple and half are white then the plant would Pp.

Question 35

MONOHYBRIDS

Answer 35

F1 (HETEROZYGOTE HYBRIDS), offsprings of P1 ( true breeding parent). They are heterozygoous for one particular character (color) being followed in the cross
( how mendel discovered his law of segregation)

Question 36

MONOHYBRID CROSS

Answer 36

Cross between 2 F1 heterozygous hybrids for one particular character ( color)

Question 37

DIHYBRIDS

Answer 37

The F1 generation (heterozygote) of a P1 parent ( true breeding) that has been cross for 2 characters ( color and shape)
( Mendels 2nd law of independent assortment)

Question 38

DIHYBRID CROSS

Answer 38

The cross between 2 F1 hybrids heterozygotes for 2 characters

Question 39

DEPENDENT ASSORTMENT

Answer 39

If a dihybrid cross occured in the same pattern/combination of alleles as they were inherited

Question 40

INDEPENDENT ASSORTMENT

Answer 40

. Each pair of alleles segregates independently of each other pair of alleles during gamete formation

2 pairs of alleles for 2 different character segregate independently of each other : They are packed in gametes in all possible allelic combinations as long as each gamete has one allele for each gene.

. If a cross for 2 characters the alleles of each character is inherited /sorted in to gametes independent of the other allele of genes

Question 41

The phenotypic ratio of a dihybrid cross

Answer 41

9:3:3:1 ( 16 different possibilities of gametes from four possible classes)