Genetics & Biotech Review for 2012- Answers.docx - nimitz126

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Dec 12, 2012 (4 years and 8 months ago)

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Genetics
& Biotechnology Review for 2012


Use this key for the following genetic problems.

T= tall



t= short


B=Black


b= brown

Y= yellow


y= green


H= short haired

h= long haired

S= smooth


s= wrinkled


C= curly haired

c= straight haired

R= round


r=
oval



P= pugged nose

p= round nose


Write the genotype for the following:

Use the key above

1.

Homozygous tall, green_____
TTyy
____________________

2.

Heterozygous round, hetetrozygous smooth____
RrSs
_____________

3.

Brown, heterozygous black________________________
______

4.

Homozygous pugged nose, heterozygous short haired________________

5.

Homozygous curly haired, heterozygous short haried, homozygous black hair

____________________________________














Write the phenotype for the following:

Use the key above

6.

S
SRr=__
smooth, round
____________

7.

ppHH=_
round nose, short haired
____

8.

Ttss=________________________________________

9.

RrYy=_______________________________________

10.

BBHhcc=______________________________________


Perform the following crosses= give both the genoty
pic ratio and the phenotypical ratio:


11. Homozygous tall x Homozygous tall


TT x TT








T

T

T

TT

TT

T

TT

TT

Phenotypic ratio Tall: short



Genotypic ratio: TT: Tt: tt





4 : 0






4: 0: 0



12. Homozygous black x

Heterozygous black

(finish this)



BB x Bb




13. Heterozygous pugged nose x Heterozygous pugged nose





14. Heterozygous shorthaired x Homozygous longhaired



GENETICS PRACTICE 1: BASIC MENDELIAN GENETICS

Solve these genetics proble
ms. Be sure to complete the Punnett square to show how you got

your solution.





C


c





1. In humans the allele for albinism is recessive to the allele for normal
skin pigmentation. If two heterozygotes ha
ve children:


(Cc
xCc)


W
hat is the chance that a child will have normal skin pigment?

3/4 or 75%

What is the chance that a child will be albino?



1/4 or 25%

Genotype for
normal pigment:

CC or Cc


Genotype for albino:

cc


a.
If the child is normal
, what is the chance that it is a carrier (heterozygous) for the albino allele?
(
CAREFUL!
)




2/4 or 50%


2. In purple people eaters, one
-
horn is dominant and no horns
is

recessive. Show the cross of a purple people eater that is heterozygous

for horns with a purple people eater that does not have horns.


Summarize the genotypes & phenotypes of the possible offspring?





GENETICS PRACTICE 2: PROBABILITY PRACTICE

1. In
humans, curly hair is dominant over straight hair. A woman heterozygous for hair curl

marries a man with straight hair and they have children.

Hh x hh

a. What is the genotype of the mother? _____
_
(
Hint:
see above
)
____________________________________

b.
What gametes can she produce?_________
(
Hint:
there are 2
)
____
_______________________________

c. What is the gen
otype of the father? _______
(
Hint:
see above
)
_______________________________
____

d. What gametes can he produce?_________
(
Hint:
there

is just one
)
_____
__________________________

e. What is the probability that the 1st child will have curly hair?___
(
do a Punnett square
)________________

f. What is the probability that the 2nd child will have curly hair?_______________________

2. List all
the gametes that are possible with each of the following genotypes.

a. Aabb _____
Ab and ab
______________

d. AABb _____________________________

b. AaBB ______________
_____________ e. AAbb ________
Ab only
______________

c. AaBb ___________________________ f.
aabb _____________________________

3. What is the probability of getting the gamete (
ab
) from each of the following parents?

a. Aabb
-

you have a

1/2 chance of getting

a
and a

1
/1 chance of getting b; so, since


1/2 x 1/1 = ½, you have 1 out of 2 chance of getting ab (or you could say a 50% chance)

C

CC

Cc

c

Cc

cc





b. aaBb __________________________________________________________________

c. AaBb __________________________________________________________________

d. AABb _________
_________________________________________________________

e. AAbb __________________________________________________________________

GENETICS PRACTICE 3: Multiple alleles



You are a scientist performing the first analysis of the genetic basis for the inheritance of flower color in a
certain
species of wildflower. You begin your investigation by observing that there are four different flower
colors in the local wild population: white, red, blue and purple. Your first assumption (hypothesis) is that you
are looking at the effects of a single ge
ne, so operate under that assumption. You collect a variety of samples of
all colors, take them back to your greenhouse, and begin making crosses. Remember, you are crossing members
of a wild population

you have no idea whether any of your plants are homoz
ygous or heterozygous. Here are
the various results you obser

Hint: Before you go on to answer the questions, use the information I have given you in the
third column to make a key and work out the various genotypes for the different colors. This
one is
alot like blood type. c is a recessive for color (as in no color) B & R are both dominant
.



White X
White

All offspring always produce white flowers.

cc

x
cc

(see note
below)

Red X
Red

In some matings, all offspring produce red flowers.

In other matings, some of the offspring produce red flowers, some white,

with red flowering offspring outnumbering white flowering offspring.

Red (R) is dominant
to white (c)

Blue X
Blue

In s
ome matings, all offspring produce blue flowers..

In other matings, some of the offspring produce blue flowers, some white

with blue flowering offspring outnumbering white flowering offspring.

Blue (B) is dominant
to
white
(c)

Purple X
Purple

Always
produces a mixture of red, blue and purple flowering offspring,

with purple most frequent, followed by red and blue in roughly equal
numbers,

Blue is incompletely
dominant to Red

White X
Red

In some matings, all offspring produce red flowers.

In other mat
ings, some of the offspring produce red flowers, some white.

Red and white occur in roughly equal numbers..

Red was
heterozygous
&
__________________

White X
Blue

In some matings, all offspring produce blue flowers.

In other matings, some of the offspring

produce blue flowers, some
white.

Blue and white occur in roughly equal numbers..

(You tell me!)

White X
Purple

Always produces roughly equal numbers of blue flowering offspring

and red flowering offspring.

(Use a Punnett square for this
one)

Red X
Blue

Always produces purple offspring, but in some matings also produces

red and/or blue offspring, and/or white offspring

Depends on whether
the parents are
homozygous or
heterozygous for red
or blue

Red X
Purple

Always produces red and purple offspring,

sometimes mixed with blue.

(You tell me!)





Blue X
Purple

Always produces blue and purple offspring, sometimes mixed with red.

a.

How many alleles
are governing flower color in this plant?


b.

What color does each of these alleles produce (in other words, what colors are your homozygous
plants)?


c.

Explain the dominance relationships among your alleles, and explain the results of each of the
crosses described above.


7.

A woman has a daughter. There are three men whom she claims might have been the father of the child.
The judge in the paterni
ty court orders that all three men, the child, and the mother have blood tests. The
results are: mother, Type A; Daughter, Type O; Man #1, Type AB; Man #2, Type B; Man #3, Type O.
The mother claims that this proves that Man #3 must be the little girl’s fat
her.


a.

Is the mother correct? Why or why not?

(
She’s wrong. Nothing is proven, just shown to be
possible. Can you tell me why?)


b.

The judge isn’t satisfied, so he asks for the medical records of the people involved. He discovers
that the little girl is col
orblind. Men #’s 1 and 2 are also colorblind; Man #3 has normal color
vision, as does the mother. (NOTE: Colorblindness is X
-
linked and recessive.) Assuming that
one of these three men
must

be the father, can you now determine which of the three it is?

(Ye
s,
so tell me which one it is!)



Problems Involving Gene Interactions


1.

In cats, there is a gene which produces ticked fur (bands of different colors on each hair) called Agouti
(H). The recessive allele (h) for this gene produces hair which is a solid col
or from end to end. In
addition, there is a coat color gene which has a recessive albino allele (a) which, in the homozygote,
prevents the production of any coat color pigment, resulting in a white cat with pink eyes, the traditional
albino. Note that this

problem has described two completely different genes. These genes are unlinked.
An albino female cat is mated to a solid brown male cat. All of their offspring are Agouti. The males and
females among these offspring are allowed to freely intermate, produc
ing a flock of F
2

kittens. Predict
the phenotypic ratio for fur color among these many grandkittens.

H


Agouti


A
-

produce color



Note: in this case, any cat with an aa

h
-

solid


a
-

don’t produce color (albino)


will be albino, whether they have











a dominant
H

or a recessive
h

Parental cross


Mom is

Dad is


Fill in the Punnett square below
, & work out






HHaa x

hhAa


the ratios


















Review for test on Biotechnology

1. Define:

a)

Operon
-

a group of genes that
produce proteins that have a common function plus the regulatory
region that controls them

b)

Repressor
-

a protein that binds to (grabs onto) the operator of an operon to block RNA polymerase

from starting to cop
y

a gene. Likes to bind onto
some other subst
ance even more (like lactose) so that
it releases the operator

c)

Promote
r
-

a section of the operon where the RNA polymerase grabs on
to the DNA strand to

start
transcribing the genes into mRNA

d)

Operator
-

the on/off switch for an operon; the repressor protein
grabs onto the DNA here to block the
RNA polymerase

e)

Coding region
-

a group of genes for proteins that have the same function

f)

Activator
-

an enzyme that binds onto DNA that regulates one or more genes by helping RNA
polymerase to grab onto the DNA and start
making mRNA copies of the gene

g)

Enhancer
-

the section of the DNA that the activator grabs on to

h)

Transcription factor
-

proteins that work in groups to turn on transcription of a Eukaryote gene


2. Cells don’t need all their genes all the time. So, they reg
ulate which
__
genes
_______ get expressed


and at what ______
amount
______.


3. Compare and contrast gene regulation in Prokaryotes and Eukaryotes.

a.

Prokaryotes regulate their genes in groups

called operons
, Eukaryotes one at a time

b.

In Prokaryotes, the
control sequences are right by the genes to be expressed, in Eukaryotes
they may be

far away on the chromosome


4. Draw the
Lac

Operon.


5. What is a DNA fingerprint?

DNA that has been digested (cut up) into lots of different lengths (pieces) and run
through an agarose
gel by electrophoresis (using an electric current) to separate it into bands of different sizes, and then
stained.


6. Why is nearly every DNA fingerprint unique?


Everyone has some differences in their DNA because we all get half of ou
r DNA from Mom and half

from Dad.





7. What shows up on a gel when viewed with the naked eye?

The marker dyes



How can you make the DNA visible?


Stain

it with a dye that sticks

to DNA

and can be seen with

the

naked eye, or with a stain that will l
ight up when an ultraviolet light is shined on it.


8. How does a gel separate DNA pieces into bands
-

it acts like a giant filter,
the smaller the piece of
DNA the

farther it is able to travel through the gel, the larger, the less it can get through

9. H
ow can you figure out what size the DNA in a specific band is?

by comparing it to a band
of

DNA of

known size ( you already know what size it is)


10. Define:

a)

Restriction enzyme
-

enzyme first discovered in bacteria that cuts DNA at a specific palindromic
sequence of nucleotides

b)

Vector
-

a plasmid or virus we stick a gene into

c)

Plasmid
-

a small circular piece of DNA found in bacteria. We put genes into them using restrictions
enzyme
s and gene splicing

d)

Recombinant DNA
-

DNA
made by splicing (sticking together) DNA from two different organisms

e)

Genetic engineering
-

making changes in DNA using technology


11. Name and describe be the four steps of making a recombinant DNA.

a)

Using a restri
ction enzyme, cut the gene you want out of the chromosome it is in. Be sure to leave
“sticky ends”


b)

Using the same restriction enzyme, cut open the plasmid DNA (or the other DNA you want to use) so
that it has sticky ends that are complementary to the one
s on the gene you cut out


c)

Mix the two kinds of DNA together, so that the “sticky ends” stick to each other (A to T and C to G)

d)

Add DNA ligase to the mix to seal the two sections of DNA together


12. What is a palindrome?
A section of DNA that has the sa
me sequence whichever way you run it:






AACGTT






TTGCAA


What is a restriction enzyme?

See above