Transcript 13.1-13.3 Lecture

Chapter 13
Genes and Chromosomes
Could you be like Mike?
Environment
Genetics
Genetics vs. Environmental factors
Everyone is a product
genes and
environment
– Ex. Height
– Siamese Cat fur
Hot areas: white
Cold areas: black
Identical versus Fraternal Twins
Genetically identical
– Same fertilized egg
splits into two
Different environment
– Different food, sleep,
experiences, emotions,
sunlight
differing
traits=stronger
environmental
influence
Old Belief: Blending theory
Belief: fertilization
mixed your parent’s
genes
You are average of both
Once mixed, cannot be
separated
Events Contradicting “blending theory
You don’t always look like parents
Healthy parents have sick children
Gregor Mendel
A monk, gardener,
and high school
science teacher
1860’s, grew garden
peas
Studied 28,000 pea
plants around 8 years
Pea Plants as Subjects
Easy to grow
Little maintenance
Self-fertilizing
– Can be artificially
fertilized
Can obtain truebreeding plants
– If bred to itself,
always produce
offspring identical
to
Mendel
Studied 7
characteristics
– Pod shape: inflated or
constricted
– Stem length: tall or
short
– Other 5 are to the right
Generations
Parental Generation or Pgen:
First filial generation or F1:
Second filial generation or F2:
Green pods w/ Yellow pods
F1 generation: children
are all green
F2 generation: ¼ is
yellow, ¾ green
Defies blending theory
Mendel came up with
the concept of a
inherited unit(gene)
A
Gene A
Gene
5`
3`
Segment of DNA that encodes a functional
protein
Gene: eye color makes pigment proteins
– Alleles: different forms
– Ex. Brown vs. blue eye color
Most traits are multigenic and environmental
Ex. Hair color
Genes vs. alleles
Genes are responsible for
making a protein
Alleles are different
versions of gene
– Make the same protein
– Slightly different forms
Gene makes a protein that
makes the peas a certain
color
– One allele makes a certain
protein
Gives a green color
– Another allele makes
another version protein
Yellow color
Genes and Chromosomes
5`
3`
Chromosome: long continuous strands of
DNA
– Diploid organisms have homologous
chromosomes
– Two very similar chromosomes, one from
mom, one from dad
Holds thousands of genes at certain points
Easy to study when they’re condensed
Karyotype 1
A picture of an
organisms
chromosomes
Each human cell has
all 23 pairs of
chromosomes
Can look at picture to
detect abnormalities
and determine gender
– Amnio test on unborn
babies
Karyotype 2
White blood cells used
Add chemicals to stop
it in metaphase
Placed on slide and
treated with water
– Spread chromosomes
out
– Easier to study
Add stain which
creates unique bands
Take a picture
Karyotype..continued
Then you take
picture and cut out
chromosomes
Pair them up based
on
1. size
2. banding
patterns
3. location of
centromere
Lab: Karyotyping Activity
In pairs, you will learn how
chromosomes are actually organized
into karyotypes
A picture of a human patient’s
chromosomes were taken
Cut out and organize into a
karyotype