Transcript Slide 1 - Issaquah Connect

Genetics and Monohybrid
& Dihybrid Cross
Test Review
With your host…Ms. Turner!
Vocab
Mendel’s
Laws
Monohybrid
Cross
Dihybrid
Cross
Miscellaneous
10
10
10
10
10
20
20
20
20
20
30
30
30
30
30
40
40
40
40
40
50
50
50
50
50
Vocab: 10
Define genetics.
ANSWER
Vocab: 10 - Answer
Genetics is the study of
biological inheritance patterns
(how traits are passed from
parent to offspring) and
variation in organisms.
Vocab: 20
What does it mean for
a genotype to be
homozygous?
(I’m looking for a specific vocab
word in your answer)
ANSWER
Vocab: 20 - Answer
A homozygous genotype has
two of the same alleles
(versions of a gene).
Ex: TT or tt
Vocab: 30
What are chromosomes
made up of?
What is a gene?
ANSWER
Vocab: 30 - Answer
Chromosomes are
made of supercoiled
DNA (with the help
of proteins –
histones).
Genes are segments
of DNA that code
for a particular trait.
Vocab: 40
What is the difference
between genotype and
phenotype?
ANSWER
Vocab: 40 - Answer
Genotype is the
genetic makeup of
a specific set of
genes (the genetic
information) and
phenotype is the
physical
characteristics or
TRAITS THAT
ARE EXPRESSED.
Vocab: 50
What is a Punnett
square?
(use the correct vocabulary)
ANSWER
Vocab: 50 - Answer
A Punnett square is
a grid system for
predicting the
possible
offspring
genotypes
resulting from a
cross.
Mendel’s Laws : 10
What did Mendel call traits that
could “hide” for a generation?
What is the trait that
overshadows the trait that
hides?
ANSWER
Mendel’s Laws : 10 - Answer
A recessive trait can be hidden for
one or more generations and then
be expressed only when two
alleles for the recessive trait are
inherited.
A dominant trait will be expressed
if one copy of the gene (or allele)
is present.
Mendel’s Laws : 20
What does the Law of
Segregation state?
ANSWER
Mendel’s Laws : 20 - Answer
The Law of Segregation states the
organisms inherit two copies of each
gene (one from each parent) and that
organisms donate only one copy of
each gene in their gametes…THUS the
two copies of each gene
segregate, or separate, during
gamete formation.
Mendel’s Laws : 30
How is Mendel’s Law of
Segregation shown while
using Punnett squares?
ANSWER
Mendel’s Laws : 30 - Answer
When the parent genotypes
are split (segregated) and
one letter is written next to
each box, it is showing that
the offspring will only
inherit one copy of a gene
(allele) from each parent.
Mendel’s Laws : 40
How do Punnett squares show
Mendel’s Law of Independent
Assortment?
ANSWER
Mendel’s Laws : 40 - Answer
Different traits appear to be
inherited separately – by showing
all of the possible
combinations for offspring
genotypes (filling in the squares)
you show that it is random which
genes are inherited.
Mendel’s Laws : 50
When in meiosis does the Law of
Independent Assortment take
place?
When in meiosis does the Law of
Segregation take place?
ANSWER
Mendel’s Laws : 50 - Answer
The Law of Independent
Assortment takes place in
Metaphase (could be I or II, we
stressed it in I when the tetrads
straddle the metaphase plate).
The Law of Segregation takes
place in Anaphase II when sister
chromatids split leaving you with 1
copy of each chromosome. (I
could see Anaphase I also being
an acceptable response )
Monohybrid Cross : 10
Write three different
genotypes:
Homozygous Dominant
Heterozygous
Homozygous Recessive
(you can use any letter)
ANSWER
Monohybrid Cross : 10 - Answer
Homozygous Dominant - TT
Heterozygous - Tt
Homozygous Recessive - tt
Monohybrid Cross : 20
In Nicotiana plants, the allele for
green leaves (G) is dominant
over the allele for yellow leaves
(g). Make a Punnett square to
show the cross for a GG plant
and a Gg plant and write the
genotypic and phenotypic
ratios.
ANSWER
Monohybrid Cross : 20 - Answer
G
G
G
GG
GG
g
Gg
Gg
Genotypic Ratio – 2:2:0 or 1:1:0
Phenotypic Ratio – 4:0 or 1:0
Monohybrid Cross : 30
If you perform a cross
between two heterozygous
individuals, what percentage
of the offspring would
express the recessive trait?
(you can do a Punnett square to figure it
out, but you need to write your
answer in a percent) ANSWER
Monohybrid Cross : 30 - Answer
25% (1/4) of the offspring
would express the recessive
trait.
G
g
G
GG
Gg
g
Gg
gg
Monohybrid Cross : 40
Determine the possible genotypes
and phenotypes of the offspring
for a family whose mother has a
smooth chin and whose father
has a cleft chin. If that’s all the
information I give you…what should
you do…
Cleft Chin (L)
ANSWER
Smooth Chin (l)
Monohybrid Cross : 40 - Answer
l
l
Possible
L
Ll
Ll
genotypes:
L
Ll
Ll
Ll or ll.
L
l
l
Ll
ll
l
Ll
ll
Monohybrid Cross : 50
A husband and wife recently returned home from the
hospital with their newborn and are starting to think
that maybe the baby is not actually their own.
Neither the husband nor the wife has a widow’s
peak, but their baby does have a widow’s peak.
Determine the genotypes of the mother and father
and the possible genotypes and phenotypes for any
child of theirs.
Free Ear Lobes (E)
Attached Ear Lobes (e)
Could the baby be theirs?
ANSWER
Monohybrid Cross : 50 - Answer
No, the kid couldn’t theirs. They do not have the
dominant allele or else they would express it.
Milkman???
e
e
e
ee
ee
e
ee
ee
Dihybrid Cross : 10
What is a dihybrid cross?
ANSWER
Dihybrid Cross : 10 - Answer
It’s a cross that shows the
inheritance of TWO traits.
Dihybrid Cross : 20
In rabbits, grey hair (G) is dominant to
white hair (g).
Also in rabbits, black eyes (B) are
dominant to red eyes (b).
What would the phenotype be
for a rabbit with the genotype
Ggbb?
ANSWER
Dihybrid Cross : 20 - Answer
Ggbb would have a phenotype
of grey hair and red eyes.
Dihybrid Cross : 30
In rabbits, grey hair (G) is
dominant to white hair (g).
Also in rabbits, black eyes (B) are
dominant to red eyes (b).
What would be the possible gametes
for a rabbit with the genotype Ggbb?
ANSWER
Dihybrid Cross : 30 - Answer
Gametes for Ggbb:
Gb
gb
(use FOIL to make sure you get
all the combinations)
Dihybrid Cross : 40
In rabbits, grey hair (G) is dominant to
white hair (g).
Also in rabbits, black eyes (B) are dominant
to red eyes (b).
Use a Punnett square to show a
cross between a male rabbit
with the genotype GGbb with
a female rabbit with the
genotype ggBb.ANSWER
Dihybrid Cross : 40 - Answer
gB
gB
gb
gb
Gb
GgBb
GgBb
Ggbb
Ggbb
Gb
GgBb
GgBb
Ggbb
Ggbb
Gb
GgBb
GgBb
Ggbb
Ggbb
Gb
GgBb
GgBb
Ggbb
Ggbb
Dihybrid Cross : 50
Show the parent cross and
Punnett Square that would
give you a phenotypic ratio of
9:3:3:1.
(Use any letter)
ANSWER
Dihybrid Cross : 50 - Answer
MT
Mt
mT
mt
MT
Mt
mT
mt
MMTT MMTt MmTT MmTt
MMTt MMtt MmTt Mmtt
MmTT MmTt mmTT mmTt
MmTt Mmtt mmTt mmtt
Miscellaneous: 10
True or False:
Environment has no effect on
an organism’s traits.
ANSWER
Miscellaneous: 10 - Answer
False
Environment DOES have an
effect on an organism’s traits.
Click Here 
Miscellaneous: 20
Put these 6 items in order from
LARGEST to SMALLEST:
DNA, Chromosomes, Human
Body, Genes, Cells, Nucleus
ANSWER
Miscellaneous: 20 - Answer
Human Body, Cells, Nucleus,
Chromosomes, Genes, DNA
Miscellaneous: 30
Draw a pair of single-stranded
homologous chromosomes that
have two genes on it: hair texture
(T) and hair color (H).
The genotypes for hair texture is
heterozygous and for hair color is
homozygous dominant.
ANSWER
Miscellaneous: 30 - Answer
It doesn’t matter the
location you choose for
the genes, however, the
pairs need to be in the
same location on the two
chromosomes (in other
words, the alleles for hair
color should be in the
same spot on the two
chromosomes).
Miscellaneous: 40
What are the four phenotypic
categories for a dihybrid cross?
(when we write a dihybrid phenotypic ratio
it has four slots, what do those four slots
represent if you have to describe it using
words?)
ANSWER
Miscellaneous: 40 - Answer
Expresses the ____ trait for trait #1,
and the ____ trait for trait #2
Dominant, Dominant
Dominant, Recessive
Recessive, Dominant
Recessive, Recessive
Miscellaneous: 50
If the mother of a family is ‘normal’ but
carries the recessive gene for cystic
fibrosis and the father is also normal and
does not carry the gene for cystic fibrosis,
what are the chances of them having a
child with a cystic fibrosis?
Cystic Fibrosis (has C.F. Disease) (f)
Normal (no C.F. Disease) (F)
ANSWER
Miscellaneous: 50 - Answer
Mother: Ff
Father: FF
F
F
F
FF
FF
f
Ff
Ff
They have a 0% chance of having
a child with Cystic Fibrosis
because you need to have the
genotype ff to express that trait.