Download Unit: Human Genetics - Each species has a specific number of

Unit: Human Genetics
Human Chromosomes
- Each species has a specific number of chromosomes
Humans = ___
- Where do we get them? _____________________________________
- What type of cell is involved in sexual reproduction? _____________
- Gametes have __________________ of chromosomes (___)
Haploid (n)
- They come together during fertilization to give us _____ chromosomes
Diploid (2n)
23 + 23 = 46
- We have two types of chromosomes:
1. Autosomal chromosomes (aka ___________)
- All chromosomes other than _______________
- 22 pairs
2. Sex chromosomes
Sex Determination
- What determines a baby’s sex? ________________
- Only _____ pair
Could be X or Y
Female = ______
Male = _____
- What sex chromosomes can men and women pass on?
Women = only X
Men = X or Y
- Who determines the sex of the baby? Male or female? _________
- What are the chances a baby will be a boy? A girl? _________
- In humans 2 of the 46 chromosomes are sex chromosomes (XX or XY)
- The other ____ chromosomes are called autosomes.
Autosomes
- Autosome = Opposite of sex chromosome
Karyotypes
- How do scientists study chromosomes? They use a _______________.
- A karyotype is a picture of chromosomes grouped
____________________________________.
How do they make a karyotype?
- Cells are photographed during _____________.
- The chromosomes are cut out of the picture and put in pairs
- The pairs are in order from
____________________________________.
Uses of karyotypes
Disorder
Human Heredity
Pedigrees
Uses of Pedigrees
-What do scientists look for?
– Are there 46 chromosomes?
– Are there 2 identical pairs of each autosome and 2 sex chromosomes?
– Are any chromosomes missing pieces or mixed up?
Uses:
- To detect __________________________.
- For ____________________ prospective parents
- Disorder = ______________________________
- What is heredity? ________________________________________
- A _________________________ is used to observe the inheritance of a
given trait over generations in a family.
- A pedigree shows ______________________________________.
- Genetic counselors use pedigree charts to determine the _____________
of family members.
Label:
A circle= ____________
This shows the
relationship of
______________
______________
_______
__________ =
expresses
the trait.
Polygenic Traits
This represents a __________
A square = _________.
___________ =
does not
express the
trait.
- Not all human traits are controlled by a ______________________.
Example: Aa
- Some traits are polygenic (trait controlled by ____________________)
Example: AaBbCc
Environmental Factors
Sex-linked Traits
Sex-linked Traits
in Males and Females
- What else can affect traits?
- Environmental factors
For example, __________________________________________
Human traits can be:
- __________________________________ or
___________________________________
- Some genes are only carried on the sex chromosomes
= _______________________________.
- More than 100 sex-linked genetic disorders have now been mapped to
the ______________________________.
- The Y chromosome is much ___________ than the X chromosome.
- It appears to contain only a few genes.
- Sex-linked traits are more likely to be passed on to males than females.
Why?
- Females have 2 X chromosomes
Possible genotypes:
XHXH
normal
XHXh
XhXh
___________
__________
- Carrier carries the recessive gene but does not ___________________
(heterozygous)
- Males have only ______ X chromosome
- ___________________does not carry many genes
- Possible genotypes:
XHY
Sex-linked Disorders
XhY
Normal
___________
- For a recessive allele to be expressed in females, they must have 2
copies: X __ X___
- Since males have just one X chromosome, ______ X-linked alleles are
expressed even if they are recessive: X____Y___
Common sex-linked recessive traits:
- Colorblindness = Cannot see _________________________
- ________________ = blood cannot clot due to lack of normal blood
clotting protein
Color-blindness
- Found in about 1 in 10 males vs. 1 in 100 females
Female genotypes:
XCXc = Carrier
XcXc = _____________
Males genotypes:
XCY = ______________
XcY = Colorblind
Sex-linked Problems
Example 1: Colorblindness
XCXc
(carrier)
Hemophilia
x
XCY
(normal)
Example 2: Hemophilia (Blood does not clot, so you bleed longer)
H= ________________________________________ h= hemophilia
Carrier mother & Hemophiliac Father
XHXh
XhY
- Hemophiliacs can bleed to death from cuts and may suffer internal
bleeding if bruised.
Autosomal Traits
- Result from genes carried on autosomes
Affect males and females equally
- Genetic disorders can be caused by a recessive, dominant, or
codominant allele.
Recessive alleles
- Phenotype expressed only by ___________________ recessive (tt)
- Heterozygote (Tt) acts as a ________________
Cystic fibrosis
- Caused by a __________ of 3 DNA bases
- Defective gene found on chromosome 7
- The protein made is not normal
- Thick mucus produced that clogs lungs; digestive problems; get
infections easily
- Dominant alleles are expressed ______________________________
____________________________________________
- If a disorder is caused by a dominant allele:
- The protein produced by the abnormal gene inactivates the
Dominant alleles
normal protein or ____________________________________________
Huntington's Disease
- Lose ability to walk, talk, and think (___________________________)
- Caused by genetic mutation on chromosome 4
Codominant alleles
- _________________________ are expressed
Sickle Cell Disease
- Just ______________________ is changed in a gene on chromosome 11
- Causes red blood cells to be sickle shaped rather than disc shaped
- They get stuck in blood vessels & cause damage to tissues
Sickle Cell Disease
& Malaria
Genetic and Chromosomal
Disorders
Mutations
Types of Genetic
Mutations
- Individuals with both normal and sickle cell alleles are ___________
_________________________________________
- Malaria is a disease caused by a __________________
- In areas like Africa where malaria is present,________________ have
an advantage
- They survive and pass on the sickle cell allele
- What causes these disorders?
- _____________________: any change in the genetic material
- can be caused by factors such as UV light, radiation, X-ray, chemicals
Mutation can occur at two levels:
1) Genes
2) Chromosomes
- DNA/ Gene Mutation
involves changes in one or a few nucleotides
1) ______________________
- a change in single DNA base sequence
Ex: Our big dog bit the man
Our big dot bit the man
2) _______________________
- a base is “added” or “deleted” causing a
“shift” of sequence
Ex: Our big dog bit the man
Our rbi gdo gbi tth ema n
Oub igd ogb itt hem an
Chromosome mutation
- Involves changes in _________________________________________
Types of Chromosome
Mutations
Deletion = a piece is lost
Duplication = a piece is duplicated
Inversion = a piece is switched
Translocation = a broken piece attaches to another chromosome
Nondisjunction = ____________________________________________
Nondisjunction
Meiosis I:
Nondisjunction
Extra chromosomes
Turner Syndrome
YO
“Super Female”
Klinefelter Syndrome
Down Syndrome
Missing chromosomes
- One too few chromosomes (__________)
- Sterile (cannot have children), shorter than average, heart defects,
premature aging, shorter lives
YO = _______________
- No babies have been reported being born without an X chromosome
- ______________________= only one chromosome (XO)
- ____________= one too many chromosomes (XXX, XXY, trisomy 21)
- ________ Condition
- Tall, small head, increased strength, possible retardation, infertile
- ____________ condition
- Most from non-disjunction in ______________
- Tall, some mental slowness
- Poor male sex organ development; breast development; usually sterile
- Trisomy _______
- 3 copies of chromosome 21
- Mild to severe mental retardation
- Many lead productive lives