Exam #4 - Genetics Flashcards by Anthony Kemmer

Is blending a correct model of inheritance?

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Why did Gregor Mendel study pea plants?

1) Peas are eukaryotes
2) Cheap and easy to handle
3) Within a short amount of time, you can generate the next generation. Within a year or less

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A character = ?

A characteristic

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Flower color is a ________?
The plant height is a ________?
The pea color is a _________?
The pod shape is a __________?

Characteristic. These are all TRAITS

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Variety is a TYPE of _________.

character

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Red flowers….white flowers…tall height…small height…yellow peas…green peas…these are ________.

varieties. (Varieties are more SPECIFIC)

**Trait: Flower Color
**Variety: Red Flower (MORE SPECIFIC = VARIETY)

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T/F: A pea plant can fertilize itself

True

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In nature: self pollinate

Mendel: ____ _______

cross pollinate

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Start with a parent that produces offspring just like itself…this is called _____ _______.

true breeding

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Start with true breeding, but take two _______ true breeding varieties and _____ them. See what you get!

different, cross

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This was Mendel’s experiment:
Take a true breeding parent of one ______, and cross it with a true breeding individual of another ______. Same characteristic, but two different _______. And that will produce an offspring.

variety

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Since this offspring is a parent of two varieties, it is known as a ______.

hybrid.

A hybrid generate by cross pollination

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The hybrid is then allowed to ____ ________.

This last group of offspring is analyzed to see what conclusion we can draw.

self pollinate

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The original generation is called _.
The hybrids are called __.
The final set of offspring is called __.

P
F1
F2

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Mendel’s experiment #1:

Crossed a true breeding individual with ______ seeds with a true breeding individual with _______ seeds.

round, wrinkled

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What are the offspring? (F1)

All round

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What were the results of the final offspring? (F2)

Round, wrinkled. 3:1 ratio

Wrinkled came back…

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What conclusions did he draw from experiment #1?

1) His observations contradicted the blending model
2) Characters/traits are produced by ‘heritable factors’ that are DISCRETE

**Today we know that ‘heritable factors’ = genes

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Experiment #1 conclusions:

1) Characters/traits are produced by ‘heritable factors’ that are DISCRETE
2) An organism has ___ genes for each trait.
- ___ from each parent

Today we know:
We inherit a pair of ________ _________
-They have the _____ GENES!

two
one
homologous chromosomes
SAME

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Why different phenotypes for a trait?

A gene has different “versions” or alleles (round, wrinkled)

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Experiment #1 conclusions:

1) Characters/traits are produced by ‘heritable factors’ that are DISCRETE
2) An organism has TWO genes for each trait.
3) Genes have alternate versions called _______.

Today we know:
A gene can vary in its ________ ________.

alleles

nucleotide sequence

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Based on mender’s experiment…
Round seed phenotype: _________
Wrinkled seed phenotype: _________

DOMINANT

Recessive

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Experiment #1 conclusions:

1) Characters/traits are produced by ‘heritable factors’ that are DISCRETE
2) An organism has TWO genes for each trait.
3) Genes have alternate versions called ALLELES
4) When different alleles are TOGETHER:
- Dominant allele: affects ________.
- Recessive allele: DOES NOT affect ________.

appearance

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Experiment #1 conclusions:

1) Characters/traits are produced by ‘heritable factors’ that are DISCRETE
2) An organism has TWO genes for each trait.
3) Genes have alternate versions called ALLELES
4) Dominant allele: affects appearance
5) Alleles separate during gamete production.
- This is called ____ __ _________.

Today we know:
_______ __________ separate during meiosis I

Law of segregation

homologous chromosomes

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Particulate Model of Inheritance: | 'Genetic material' is composed of UNITS which are passed on to offspring, and which retain their ________.

IDENTITIES

Why 3:1 in F2?

USE A PUNNET SQUARE!

Punnet Square: predicts the result of a cross by accounting for _______ fertilization.

random

______ is the process of change in the genetic code.

mutation

Every allele today came about by _______.

mutations

_______ is the physical appearance of an organism.

phenotype

The genes that you have, or genetic makeup, is called _______.

genotype

Your _______ is what gives you your ________.

genotype, phenotype

The ________ of the parents are purple flower and white flowered plants

phenotypes

The ________ is two dominant alleles, two purple alleles, two recessive alleles.

genotype

If you have two of the same allele, you are said to be _________.

homozygous

If you have two different alleles, you are said to be ________.

heterozygous

A true breeding individual is _________.

homozygous

The F1 is _________.

heterozygous

Among the F2, we have some _________ and some ________.

heterozygotes and heterozygotes

A ________ ratio means the ratio of different genotypes.

genotypic

How many different genotypes were in the purple, white flower cross?

3 Homozygous dominant Heterozygous Homozygous recessive Present at a 1:2:1 ratio

When the parents differ in one trait, it's called a ________ cross.

monohybrid cross | ex: Pea shape: round and wrinkled

when the parents differ in two traits, it's called a _________ cross.

dihybrid cross | ex: Flower color and Pea shape

Breeding an organism of **unknown genotype** with a **recessive homozygote** is called a ________, because it can reveal the genotype of that organism.

testcross

Mendel's Experiment #2 Follow _____ and _____ traits

shape and color

Hypothesis #1: the genes are physically ________.

connected

When the F1 generation goes to make offspring, what must occur?

Law of segregation

Hypothesis #2: The genes are ___ physically connected.

not

The conclusion was that...

Pea color and pea shape are NOT connected

A pair of alleles (pea color) MAY sort to gametes independently of other pairs of alleles (pea shape). This is known as...?

Law of independent assortment

A pair of alleles (pea color) MAY sort to gametes independently of other pairs of alleles (pea shape). This is known as the LAW OF INDEPENDENT ASSORTMENT Today we know: Each pair of homologous chromosomes sorts randomly during ________ _.

meiosis I

Will the law of independent assortment apply to any two pairs of alleles?

***Only if the gene is on different chromosomes*** | Pea color and pea shape are on different chromosomes

If the genes are on the same chromosome, what doesn't apply?

Law of independent assortment

If two different genes are on different chromosomes, they will sort independently of each other and will allow for the law of independent assortment. If two different genes are on the same chromosome, then it will not sort independently. They will sort together because they're physically ________.

connected

Why is it that the dominant allele affects the phenotype? | The recessive allele is not producing a functional _______.

protein.

The dominant allele produces a functional protein, which is why we see the dominant allele, as opposed to the recessive allele, which produces an ineffective _______.

protein

The recessive phenotype is not caused because you have recessive alleles, it's because you DON'T HAVE.....?

Dominant alleles

If the heterozygote looks in between the two dominant phenotypes, then we say the dominance is ________. Ex: Pink flower has C^r (red color) and C^w (white color)

incomplete

When a heterozygote shows intermediate phenotype in between the two homozygous individuals, it's called _______ ________.

incomplete dominance. | The flower is pink instead of red or white

Mendel discovered ______.

genes

Mendel identified that characters are identified by _____.

genes

If you have two alleles, only ___ will be placed in the egg and ___ will be placed in the egg.

one

Only one will get placed into the sperm, and only one will be given to your offspring. This is because the cell division that produces your gametes, the meiosis separates the gene pair, specifically meiosis I. That is called...?

Law of segregation - only give one to your offspring

When homozygous dominant individuals and heterozygous individuals look the same, this is called _______ _________.

complete dominance

When both alleles affect a phenotype, it's called ________.

codominance

How many different alleles can one person have for a gene?

TWO - one from mom, one from dad

________: a CHANGE in the nucleotide sequence of a gene

Mutation

T/F: A dominant allele is not necessarily most common in the population

TRUE. Most peas have the genotype: homozygous recessive. So the dominant allele is quite rare in the pea plant population. So again, there's NO rule saying the dominant allele is the most common allele.

Some phenotypes result from more than 1 gene. This called...?

Polygenetic inheritance. 3 different GENES give rise to different eye color Skin color comes about from 6 different GENES. ***NOT alleles*** *GENES!!!! Each gene has different alleles, now think of the broad range of possible human skin colors

Phenotype is the result of...? (2)

1) Genotype - genes | 2) Environment - how much sun you've recently gotten

The greatest number of different alleles for a gene that a single person can have is _?

Mendel observed traits, NOT __________.

chromosomes

The __________ ______ of ________ says that the genes are located at specific positions on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns.

chromosomal theory of inheritance

Thomas Morgan's experiments | He used _________.

fruit flies

Some of the characters Morgan observed were: (3)

1) eye color 2) body color 3) wing shape

_____ ____ phenotype: typically found in nature, resulting from 'normal' allele

wild type

______ phenotype: occurs when a mutation produces a new allele

mutant

Experiment #1 conclusions 1) ___ allele is dominant to the white allele 2) fly eye color is linked to ___ 3) fly color gene is ___-linked

red sex sex

What's the first thing a parent does when it goes to make the next generation?

Law of segregation

A gene on a sex chromosome is called ...?

Sex linked gene

Which parent, male or female, determines the sex of the offspring?

Male (XX).

What is the ratio of males to females of any cross?

50/50

***Who usually shows a recessive phenotype?***

MALES. **For X-linked genes, usually it's the male who shows the recessive phenotype.**

``` A sex linked gene is a gene on the... X-chromosome Y-chromosome Either the X or the Y Both the X and the Y ```

**Either X or the Y**

For an X-linked gene, who usually shows the recessive phenotype?

MALES

The ____ method is a way of determining the possible gametes when looking at two different genes: body color and wing shape. - You take the first allele of each gene - Then the two outer alleles - Then the two inner allele - Then the last two alleles of each gene

FOIL

Experiment #2 conclusions _________ _________ does NOT apply, because the body color and wing shape genes are linked (they're on the same chromosome)

Independent assortment

_______ _____: genes located on the same chromosome

linked genes

________ _______ 'unlinks' linked joins, and then rejoins them. But not with the same allele, but with the allele with the homologous chromosome.

Crossing over

Genes are recombined in TWO ways: 1) ________ ________: - -genes on different (non homologous) chromosomes 2) ________ _____: - -genes on homologous chromosomes

independent assortment | crossing over

The body color and wing shape genes on drosophila are: 1) on the same chromosome 2) on different chromosomes 3) they're capable of independent assortment 4) they're sex linked 5) two of these answers

1) on the same chromosome

In the experimental scheme used by Gregor Mendel, the parental generation is ____-_______ to generate the F1 generation.

cross-pollinated

If an allele is recessive, then it...?

only affects the phenotype when the second copy of the gene is ****recessive****

The law of independent assortment applies to the pea plant seed color and seed shape genes because...?

the genes are on different chromosomes

The pea plant seed color exhibits _______ dominance.

complete

An X-linked gene is...?

always found on the X chromosome

Exam #4 - Genetics Flashcards

(96 cards)