Week 14-Genetics

Question 1

What is a chromosome?

Answer 1

the DNA molecule is packaged into thread-like structures called chromosomes

Question 2

How many chromosomes do human cells have and where did they come from?

Answer 2

46- 23 pairs

23 from oocyte and 23 from sperm

Question 3

What occurs and what is the significance of “crossing over” during meiosis?

Answer 3

It happens when paired homologs, or chromosomes of the same type, are lined up

They will connect and exchange some genetic information

This information should be at the same location on the chromosomes

This allows for genetic variation in the gamete

Question 4

What are autosomes?

Answer 4

first 22 Pairs of chromosomes

determine all other body features

Question 5

What are the sex chromosomes?

Answer 5

23rd chromosome

determines sex of baby

Question 6

What is X inactivation? Why is it important?

Answer 6

While males get one X, females get 2 x’s

Females will have to completely turn off one X

important because it allows for women to not have twice the amount of genes that they are supposed to have

Question 7

The first 22 pairs of chromosomes are each paired homologous chromosomes. What does this mean?

Answer 7

Each chromosome pair will code for same type of information

so information on male side of chromosome 1 is same as info on female side of chromosome 1

Question 8

What is a gene?

Answer 8

unit on a chromosome that codes for a specific trait

Question 9

Where are specific genes located?

Answer 9

chromosomes

Question 10

What do genes code for?

Answer 10

specific traits/ proteins

Question 11

What does it mean when someone has a “genetic” disease or disorder?

Answer 11

Someone has abnormal genes or chromosomes

somewhere something went wrong to make mutations

Question 12

Genotype

Answer 12

genetics/genes in person

what you are made of

Question 13

Phenotype

Answer 13

What you show physically

physical characteristics

Question 14

Describe an allele. Do all genes (characteristics) have alleles?

Answer 14

alternate forms of a trait

(tongue rolling or not tongue rolling)
(dimples or no dimples)

Question 15

Describe simple inheritance involving dominant and recessive alleles (dominant allele and recessive allele)

Answer 15

one allele is dominant and one is recessive

dominant allele will be the one that will be demonstrated on human

dominant will completely mask the recessive allele

Question 16

What does it mean to be homozygous for a trait that has 2 alleles?

Answer 16

Both parents gave you dominant or both recessive
Same alleles

DD
or
dd

Question 17

What does it mean to be heterozygous for a trait that has 2 alleles?

Answer 17

One parent gave dominant and one recessive
Different Alleles

Dd

Question 18

Briefly describe co-dominance inheritance.

Answer 18

More then 1 allele that has dominance

Question 19

Briefly describe polygenic (complex) inheritance.

Answer 19

Many genes contribute to a trait
environmental factors can affect as well

Question 20

Give an example of Co-Dominance inheritance

Answer 20

Blood typing-

A and B are dominant
O is recessive

Only way to have O blood is to be completely recessive, if just one A and/or B appears then that is your blood type

Question 21

Give an example of Polygenic inheritance

Answer 21

eye color

skin color

hair color

Question 22

Be able to fill in and interpret a Punnet square (predict inheritance)—per class project

Answer 22

______D d

D | DD Dd

d | Dd dd

Question 23

How is an Autosomal Recessive genetic disorder typically inherited?

Answer 23

When both parents carry one recessive allele unknowingly and child gets both recessive alleles

Father and mother both Rr, child gets rr genetics from them

Question 24

What does it mean to be a carrier of a recessive genetic disorder?

Answer 24

Have the receive disorder allele

Must be either Rr or rr

where r= recessive and R=dominant

Question 25

What is the significance of an Autosomal Dominant genetic disorder—what would the inheritance pattern be?

Answer 25

very Rare

Dominant allele will always show- so most people who show genetic disorder choose to not have kids

in Huntington- shows in age 45, so father may not even realize he has it until already has kids

all you need is the one dominant allele to get this disease

Question 26

What is sex-linked (X-linked) inheritance?

Answer 26

inheritance pattern comes from sex chromosome, not the first 22

Question 27

Describe inheritance of a recessive X linked disorder.

Answer 27

mom will more likely give recessive allele to boys

mothers get two x’s and turn one off, boys only get one x,

if mother accidentally gives recessive x allele to child then they might get it as well without being able to turn it off

Question 28

Describe why the sperm determines sex of the offspring

Answer 28

Mother will always give X chromosome (XX)

father could either give x or y(XY), meaning boy(XY) or girl(XX)

Question 29

Missesnse mutation

Answer 29

Base substitution

Codes for wrong amino acid

Question 30

nonsense mutation

Answer 30

Base substitution

Codes for stop codon

Question 31

silent mutations

Answer 31

Base substitution

Still get same amino acid

Question 32

insertion mutation

Answer 32

Frameshift mutation

insert a base-results in all bases shifting completely forward 1

Question 33

deletion mutation

Answer 33

Frameshift mutation

a base deletes- results all bases shifting completely back 1

Question 34

duplication mutation

Answer 34

Frameshift mutation

a portion of the DNA is abnormally copied one or more times

Question 35

triplet mutation

Answer 35

repeat expansion

will keep repeating same codon
(ccg,ccg,ccg,ccg)

Question 36

Differentiate between a spontaneous mutation

Answer 36

Random mistakes that occur at a low rate

in replication of dna

Question 37

Differentiate between a induced mutation

Answer 37

produced by agents called mutagens

Mutagens will increase the mutation rate above
the spontaneous mutation rate

Question 38

What is a chromosomal abnormality?

Answer 38

something that affects the entire chromosome

so all 10,000 proteins on it

Question 39

What occurs in a numerical chromosomal
abnormality?

Answer 39

Should have 23 pairs- 2 on each pair

If you have an extra chromosome on one pair

(extra chromosome on pair 2 = Down syndrome)

Question 40

Why are there so few chromosomal disorders?

Answer 40

Most do not allow for development of embryo - so baby would die before it was born