BIO 111 FINAL EXAM

Ch. 12-?

Mendel documented what particular mechanism of inheritance?

complete dominanceis

What plant did Mendel use to study complete dominance?

garden peas

Mendel established 2 fundamental laws of inheritance, what are they?

1. Independent Assortment

2. Segregation

Why did Mendel work with pisum sativum? What did this ensure?

controlled breeding (which plant mated with one another)
large quantities were cultivated simultaneously

ensured NO results due to chance

Normally peas ____________, but Mendel manually _____-__________ plants in order to control mating!

self fertilize, cross-pollinate

Definition of character; what is it similar to?

heritable feature (flower color); phenotype

trait definition

variant of a character (a purple/white flower)

Locus (loci) definition

specific location on a chromosome that contains a gene.

alleles

different versions of a gene that determine specific traits. (blue vs. brown eyes)

genotype

the genetic makeup of an organism (PP, Pp, or pp)

Mendel discovered that inheritance is an ____-__-_________ pattern; never “lilac”.. only purple or white colors

all-or-nothing

What are some other descriptions of “all or nothing” inheritance?

discrete, either-or

Mendel always started with parents that were “____ _______”, aka purebred

true breeding

What does “true breeding” mean?

homozygous parents, aka always pass down a specific phenotype. (Ex: PP or pp)

Which flower color was dominant/recessive in Mendel’s experiements?

Purple was dominant, white was recessive.

List the 3 genotypes and their corresponding phenotypes for purple and white traits.

Genotype: AA Phenotype: purple

Genotype: Aa Phenotype: purple

Genotype: aa Phenotype: white

In Mendels experiments, white flowers resulted from __________ alleles

recessive

How many copies of the dominant allele is necessary to observe the phenotype?

One copy!

Being homozygous recessive for a trait means that organism is also in turn less fit. True or false?

False! This is only true in SOME cases. Some organisms can be fit even if homozygous recessive.

Two of what gene results in blue eyes?

two non-functional pigments producing alleles of the gene OCA2

The F2 generation experiences a _:_ phenotypic ratio if the P generation is true breeding parents (AA x aa). What’s the genotypic ratio?

The offspring of F2, will experience a 3:1 phenotypic ratio and a 2:1:1 genotypic ratio.

What different things make up Mendel’s hypothesis?

1. concept of alleles

2. maternal and paternal alleles

3. concept of heterozygosity

4. law of segregation

________ are alternate versions of the same gene

Alleles

________ code for character while _____ codes for traits

genes; alleles

How many alleles does an organism inherit PER characteristic from each parent?

1 from mom and 1 from dad; 2 alleles total!

What is the law of segregation?

parent gives just one allele for a gene to each gamete they produce during meiosis, ensuring offspring inherit one allele from each parent

What is hybridization?

Crossing two true breeds (aka RR x rr)

The F1 generation of hybridization can be predicted easily: Genotype is _____% Rr and and phenotype ___% purple

100; 100

What are the genotypic and phenotypic ratio of the F2 generation (following the F1 progeny cross)?

1 RR: 2Rr: 1 rr and the phenotypic ratio is 3 purple : 1 white

What does Mendel’s 2nd law say?

It states that the alleles for different traits are passed independently of one another from parents to offspring.

What kind of parents did Mendel always start with (P generation)?

true-breeding (PP or pp)

P=1 means?

event certainly happens; nothing due to chance at all

P = 0 means?

event WON’T happen (0% chance); nothing due to chance

Two alleles expressed separate but equally are what kind of dominance?

codominance

Name 2 examples of codominance

1. AB blood type - traits of A and B blood types

   1. Camellia flower - red and white SEPARATE petals

Why is huntington’s disease so easy to pass on?

Huntington’s doesn’t make itself known until people are

What kind of allele can silence a dominant allele?

mutant allele

Name 3 examples of varying dominance (lethality)

1. Huntington’s disease

2. Manx Cats (MLML all die)

3. Antennapedia mutant (legs on head in place of antennae)

Golden palomino and pink snapdragon (antirhinnum majus) are examples of what kind of dominance?

C^hC^h coat color for rabbits

Himalayan

What kind of dominance is the different coat colors for rabbits?

varying dominance (multiple alleles0

What 3 other things does sickle-cell anemia code for?ilu

1. blindness

2. heart failure

   1. liver (other organ) failure

Name an example of Pleiotropy

sickle cell anemia mutation

Describe Pleiotropy

One gene mutation affecting multiple features

Epistasis = ?

a gene at 1 locus alters the phenotypic expression of a gene at another locus

Give an example of epistasis

coat color in labradors
- black is dominant to chocolate

-ee will block B or b when inherited

What kind of dominance is height an example of?

quantitative

Within group variation (plant example) is due to ___________

nature (genetics)

Between group variation

nurture (environment)

Who provided convincing evidence that chromosomes were the location of Mendel’s heritable factor?

Thomas Hunt Morgan

Wild type vs. mutant type in flies?

Wild type = red eyes & mutant type = white eye

Morgan determined the white eye mutant allele must be located on the ____ chromosome.

X

Which sex of flies displayed the white-eye mutant trait in Morgan’s experiements?

Males

Which generation of Morgan’s experiements was the mutant trait expressed (white- eye trait)?

F2 generation of males

Males are always ______ prone to x-linked diseases. They have no “hiding” behind a carrier.

more

Which scientist had the first solid evidence that a specific gene is associated with a ch

Which scientist studied wild type and mutant type for eye color, Nobel Prize?

Thomas Hunt Morgan

What theory is responsible for deeming chromosomes as the genetic material responsible for mendelian inheritance?

Chromosomal Theory of Inheritance

“X-linked” in terms of Morgan’s experiements means what?

That the mutant allele was inherited along with the X chromosome

How did Morgan’s experiments violate Mendel’s law of Independent Assortment?

Sex and eye color were inherited together - this is because

What is the pattern of chromosome positions (loci) on traits with independent assortment ?

• traits CLOSE together: consistent independent assortment

• traits FAR APART: less independent assortment

What is the pattern of chromosome positions (loci) on traits with crossover?

• traits CLOSE together: less frequent crossover

  traits FAR APART: more frequent crossover

What were the phenotypes for wild type and mutant in Morgan’s experiements?

WT = GgLl (gray; long winged)

mutant = ggll (black; short winged)

What does unlinked genes imply about loci of genes on chromosomes?

Genes are on totally different chromosomes

When does independent assortment occur during?

meiosis

What kind of assortment do unlinked genes go through?

independent assortment

What is the phenotypic?

50% parental type offspring
50% recombinant offspring

True or false: linked genes are independently assorted.

false

True or false: linked genes always independently assort

FALSE. They never truly independently assort

What is the phenotypic ratio of linked genes when crossover occurs?

1:1:1:1

What is the actual frequency of getting recombinant offspring?

between 0% and 50%

What factor determines the recombination frequency of linked genes?

distance between 2 genes on a chromosome

______________ is the frequency with which a single chromosomal crossover will take place between two genes during meiosis.

Recombination frequency

What important scientific tool (specific to genetics) is created through recombinantion frequencies?

genetic linkage map

Recombination frequency is a function of ________ between ________.

distance; genes

Chromosome 22 or 21? - Which one is shorter?

Chromosome 21 IS shorter than 22.

Nondisjunction in meiosis I creates how many chromosome issues? what are they?

4 - all irregular! (n + 1)(n + 1)(n - 1)(n - 1)

Nondisjunction in meiosis II creates how many chromosome issues? What are they?

2 issues! the other 2 are regular(n + 1)(n - 1)

What chromosomal abnormality explains why male cats NEVER experience tortoiseshell coat color?

XIST; X chromosome random inactivation (only affecting females)

trisome 21 (_____ ________)

• characteristic ____ and limb features

• Increased risk of ___________ (blood cancer)

• issues with immune, ___, ________ system

  • generally very ________

trisome 21 (down syndrome )

• characteristic face and limb features

• Increased risk of leukemia (blood cancer)

• issues with immune, GI, nervous system

  • generally very social

What sex does Triple X syndrome affect?

Female

What deformity causes triple X syndrome?

an extra X chromosome at pair 23Wh

What causes Trisomy 21?

extra chromosome at pair 21

What percent of Triple X goes undiagnosed?

90%

Which is more serious, Triple X or Turner’s?

Turner’s!

1/2500 children are born with _______; causing them to be infertile and is a permanent condition. + heart and kidney issues

Turner's syndrome

What is Klinefelter’s Syndrome? How is it treated?

Male (XXY), usually causes infertility and hypogonadism
treated with testosterone therapyWh

What is hypogonadism?

a condiiton that stops the body from producing sperm and testosterone
associated with Klinefelter’s syndrome

What is Jacob’s Syndrome?

Male (XYY); mild symptoms & usually disgnosed alongside autism

What are some symptoms of Jacob’s syndrome?

taller/stockier
acne
motor tics
learning disbilities

antisocial/aggressive behavior

What causes Cri-du-chat syndrome?

chromosome deletion

Which chromosome does Cri-du-chat affect?

Chromosome 5 (5p petite arm)

What is a distinctive characteristic of infants with cri-du-chat?

high pitched cry

What are genetic mutations?

any spontaneous change in the DNA sequence

What defines a point mutation?

change of a single nucleotide in template DNA

What are indels?

Base pair insertions or deletions that may produce frameshift mutations