Sex Chromosomes
chromosome pairs w/ DIFFERENT members in female & male
- determine sex
- develop sexual characteristics
Females have 2 __ chromosomes
X
Males have one __ & __ chromosome
X & Y
Size of chromosome Y?
small
Size of chromosome X?
LARGE, heavier
Autosomes
- both pairs of chromosomes look SAME in both sexes
- everything BUT sex chromosomes
Gender is linked to:
SEX chromosomes
Genes on X chromosome are “__-linked”
X-linked
Genes on Y chromosome are “__ -linked
Y-linked
Male-determining gene is on __ ____ chromosome
Y linked
Linkage
genes on same chromosome INHERITED together
C/O reduces…
linkage
Albinism
-autosomal recessive
FUTHER apart 2 genes are on chromosome the…
more likely they’re separated by c/o
Frequency of C/O is used in _____ ______
genetic mapping
Genes ADDRESS on chromosome
locus
Chromosome are aligned like…
beads on string
Cystic Fibrosis
- respiratory disease: produces mucus
- autosomal recessive
- most common in caucasians
treatments: chest precautions
Recessive disorders on “X” mostly show up in _____ bc:
males
: have only 1 X chromosome
Phenylalanine Hydroxylase (PAH)
breaks down phenylalanine
Red/Green Color Blind
- X recessive
- only MALES
Ppl w/2 recessive alleles CANT…
make PAH
(phenylalanine hydroxylase)
Duchenne Muscular Dystrophy
- X link RECESSIVE
- missing MEMBRANE protein
- MALES only
- muscle degeneration
- females can carry allele and pass to son
Build up of phenylalanine causes nerve cells in brain to…
develop abnormally
Progeria
- aging disorder
ex. movie JACK
Children w/ PKU may suffer from mental disabilities unless…
phenylalanine intake restricted
Most genes encode proteins w/ necessary _______….
functions
Ex.
-enzymes: mutations ALTER genes, disorder can result
Turner Syndrome
- CHANGES IN CHROMOSOME # during meiosis
- person has XO
- missing CHROMOSOME
Hemophilia
- X link recessive
- missing gene/protein
- no BLOOD CLOT factor
Missing proteins are…
needed to survive
PKU (missing enzyme)
Hemophilia (missing clotting factor)
Many traits are polygenic having…
- many genes
ex. Limb length, Alzheimer’s Disease
Humans are difficult genetic subjects bc…
1) cant control mating
2) never true F2 generation
3) have few children
4) LONG generation times
Genetic principles that apply to other organisms also apply to _______
humans
Pedigree - diagram that shows
- family relationships
- birth order
- gender
- phenotype
- sometimes genotype
Allows geneticist to determine if trait is dominant, recessive, autosomal, or x-linked
pedigree
Autosomal recessive traits, such as PKU aren’t expressed in…
heterozygous carriers
-appear equally in male/females
MOST genetic conditions are __________ ______
autosomal recessive
Huntington’s Disease
- DOMINANT autosomal
- leads to death
- 35-50 yrs old
- degeneration/death of nerve cells
Allele passes from an afflicted parent to an afflicted child in __________ disorder
huntington’s
Disorder caused by base sequence CAG repeated over & over near the start of the gene
huntington’s
In huntington’s disorder the greater # of repeats, earlier it strikes the…
more severe it becomes
Dominant lethal alleles are ____
rare
Klinefelter
- CHANGES IN CHROMOSOME # during meiosis
- 3 chromromses (XXY) MALE
- sterile MALE
- long limbs
- low verbal skills/IQ
Homozygous don’t survive…
fetal development
Sickle Cell Anemia
- autosomal recessive
- black ppl effected
- affects hemoglobin
Heterozygotes usually die before __________
reproducing
-EXCEPT HUNGINHTON’S
Phenylketonuria (PKU)
- autosomal recessive
- CANT break down phenylalanine
- missing protein
- mental shortage
- NO cure
- treatment: don’t eat phenylalanine
Arranging chromosomes in sequence by size:
karyotype