Genetics Do Now Hand in your Karyotyping Lab if you haven’t already! Take out the Video – What...
-
Upload
virginia-scott -
Category
Documents
-
view
215 -
download
0
Transcript of Genetics Do Now Hand in your Karyotyping Lab if you haven’t already! Take out the Video – What...
GeneticsGenetics
Do Now
• Hand in your Karyotyping Lab if you haven’t already!
• Take out the Video – What are genes question sheet?
• Read over the questions so you know what your looking for when your watching the video.
HeredityHeredity
Lesson 1Lesson 1
Inheritance of chromosomes• Egg + sperm zygote
egg
sperm
zygote
fertilizationmitosis &
development
meiosis
Inheritance of genes
• On the chromosomes passed from Mom & Dad to offspring are genes– may be same information– may be different information
eye color(blue or brown?)
eye color(blue or brown?)
Effect of genes• Genes come in different versions
– brown vs. blue eyes– brown vs. blonde hair– alleles
Genes affect what you look like
XBBbb
Bb Bb Bb Bb
Where did the blue eyes go??
Genes affect what you look like…
XBbbb
Bb Bb bb bb
Why did the blue eyes stay??
Genes affect what you look like…
XBbBb
BB or Bb BB or Bb BB or Bb bb
Where did the blue eyes come from??
What did we show here?• Genes come in “versions”
– brown vs. blue eye color– alleles
• Alleles are inherited separately from each parent– brown & blue eye colors are separate & do
not blend • either have brown or blue eyes, not a blend
• Some alleles mask others– brown eye color masked blue
How does this work?
eye color(brown?)
hair color
hair color
eye color
(blue?)
• Paired chromosomes have same kind of genes– but may be different alleles
In class assignment
• History and Terminology worksheet
Homework
• Determining your genes worksheet
Punnett Crosses
• Lesson 2
Do NowCheck answers from last night’s
homework (& take out last nights homework)
Read over the questions on your sheet so you know what your are looking for in the video.
Video: Where do your genes come from?
Traits are inherited as separate units
1 from Mom
1 from Dad
• For each trait, an organism inherits 2 copies of a gene, 1 from each parent– a diploid organism inherits
1 set of chromosomes from each parent• diploid = 2 sets of chromosomes
homologous chromosomes
Making gametes
BB = brown eyesbb = blues eyesBb = brown eyes
BB
bb
Bb
brown is dominant over blue
blue is recessive to brown
Remember meiosis!
B
B
b
b
B
b
How do we say it?
BB = brown eyesbb = blues eyes
Bb = brown eyes
2 of the sameHomozygous
2 differentHeterozygous
BB
B
B
bb
b
b
Bb
B
b
homozygous dominanthomozygous recessive
Punnett squaresBb x Bb
male / sperm
fem
ale
/ eg
gs
X
BB
Bb bb
BbB
b
B b
Genetics vs. appearance
• There can be a difference between how an organism looks & its genetics– appearance or trait = phenotype
• brown eyes vs. blue eyes
– genetic makeup = genotype• BB, Bb, bb
2 people can have the same appearance but have different genetics: BB vs Bb
Genetics vs. appearance
eye color(brown)
eye color
(brown)
eye color(blue)
eye color
(brown)
vs.
BB
B
BBb
B
b
How were these brown eyes made?How were these brown eyes made?
In class assignmentIn class assignment
• Genetics Practice 1: Basic genetics
HomeworkHomework
• Basics Punnett SquaresBasics Punnett Squares
Penny GeneticsPenny Genetics
Lesson Lesson 3
Lab ActivityLab Activity
2007-2008
Genetics&
The Work of Mendel
Lesson 4
Do Now
• BrainPop: heredityBrainPop: heredity
• Modern genetics began in the mid-1800s in an abbey garden, where a monk named Gregor Mendel documented inheritance in peas– used good experimental design– used mathematical analysis
• collected data & counted them
– excellent example of scientific
method
Gregor Mendel
Pollen transferred from white flower to stigma of purple flower
all purple flowers result
Mendel’s work
?
self-pollinate
• Bred pea plants– cross-pollinate
true breeding parents– raised seed & then
observed traits– allowed offspring
to self-pollinate & observed next generation
Mendel collected data for 7 pea traits
2nd
generation
3:175%purple-flower peas
25%white-flower peas
Looking closer at Mendel’s work
Parents
100%1st
generation(hybrids)
100%purple-flower peas
Xtrue-breedingpurple-flower peas
true-breeding white-flower peas
self-pollinate
What did Mendel’s findings mean?
• Some traits mask others – purple & white flower colors are separate
traits that do not blend • purple x white ≠ light purple• purple masked white
– dominant allele • functional protein
– affects characteristic
• masks other alleles
– recessive allele • no noticeable effect• allele makes a
non-functioning protein
homologouschromosomes
allele producingfunctional protein
mutant allele malfunctioning
protein
Genotype vs. phenotype
• Difference between how an organism “looks” & its genetics– phenotype
• description of an organism’s trait
– genotype • description of an organism’s genetic makeup
Explain Mendel’s results using…dominant & recessive …phenotype & genotype
F1
P X
purple white
all purple
Making crosses
• Can represent alleles as letters– flower color alleles P or p– true-breeding purple-flower peas PP– true-breeding white-flower peas pp
PP x pp
PpF1
P X
purple white
all purple
Punnett squares
Pp x Pp
P pmale / sperm
P
p
fem
ale
/ eg
gs
PP
75%
25%
3:1
25%
50%
25%
1:2:1
%genotype
%phenotype
PP Pp
Pp pp pp
Pp
Pp
1st
generation(hybrids)
Aaaaah,phenotype & genotype
can have different ratios
In class assignment
• Simple Genetics Practice Problems
Homework
• Complete simple genetics practice for homework
Gene Expression
• Lesson 5
Do Now
• Directed Reading Activity: Gene Expression
• Phenotype is controlled by both environment & genes
Color of Hydrangea flowers is influenced by soil pH
Human skin color is influenced by both genetics & environmental conditions
Environment effect on genes
Coat color in arctic fox influenced by heat sensitive alleles
In class assignment
• Gene Expression
Homework
• Regents Practice Questions
2007-2008
Beyond Mendel’s Lawsof Inheritance
Lesson 6
Do Now
• Gregor Mendel Video: HeredityGregor Mendel Video: Heredity
Extending Mendelian genetics
• Mendel worked with a simple system– peas are genetically simple– most traits are controlled by single gene– each gene has only 2 version
• 1 completely dominant (A)• 1 recessive (a)
• But its usually not that simple!
Incomplete dominance
• Hybrids have “in-between” appearance– RR = red flowers– rr = white flowers– Rr = pink flowers
• make 50% less color
RR Rr rr
RR
WW
RW
Incomplete dominance
true-breedingred flowers
true-breeding white flowers
XP
100%
100% pink flowers1st
generation(hybrids)
self-pollinate
25%white
2nd
generation
25%red 1:2:1
50%pink
Incomplete dominance
R Wmale / sperm
R
Wfem
ale
/ eg
gs RR
RW WW
RW
25%
1:2:1
25%
50%
25%
1:2:1
%genotype
%phenotype
RR
RW
RW
WW
25%
50%
RW x RW
Codominance
• Equal dominance– human ABO blood groups– 3 version
• A, B, i• A & B alleles are codominant• both A & B alleles are dominant
over i allele
– the genes code for different sugars on the surface of red blood cells• “name tag” of red blood cell
Genetics of Blood type
pheno-type
genotypeantigenon RBC
antibodiesin blood
donationstatus
A A A or A itype A antigens
on surface of RBC
anti-B antibodies __
B BB or B itype B antigens
on surface of RBC
anti-A antibodies __
AB ABboth type A &
type B antigens on surface
of RBC
no antibodiesuniversal recipient
O i ino antigens on surface
of RBC
anti-A & anti-B antibodies
universal donor
Blood donation
clotting clotting
clotting clotting
clotting clotting clotting
One gene: many effects
• The genes that we have covered so far affect only one trait
• But most genes affect many traits – 1 gene affects more than 1 trait
• dwarfism (achondroplasia)• gigantism (acromegaly)
Many genes: one trait
• Polygenic inheritance– additive effects of many genes– humans
• skin color• height• weight• eye color• intelligence• behaviors
Human skin color
• AaBbCc x AaBbCc – can produce a wide
range of shades– most children =
intermediate skin color
– some can be very light & very dark
In class assignment
• Genetics Practice 3: Blood Types Genetics
Homework
• Finish Worksheets
Sex-Linked Genetics
Lesson 7
Do Now
• Review Genetics Practice 3 OR practice co dominance and incomplete dominance
Genetics of sex
• Women & men are very different, but just a few genes create that difference
• In mammals = 2 sex chromosomes – X & Y
– 2 X chromosomes = female: XX
– X & Y chromosome = male: XY
X Y
X X
Sex chromosomes
Sex-linked traits
• Sex chromosomes have other genes on them, too– especially the X chromosome– hemophilia in humans
• blood doesn’t clot
– Duchenne muscular dystrophy in humans• loss of muscle control
– red-green color blindness• see green & red as shades of grey
X Y
X X
Sex-linked traits
XH Ymale / sperm
XH
Xhfe
mal
e / e
gg
s XHXH
XHXh
XHY
XhYXHXh
XH
Xh
XHY
Y
XH
XHXH XHY
XHXh XhY
sex-linked recessive
2 normal parents,but mother is carrier
HH HhxXHY XHXh
Dominant ≠ most common allele
Polydactylydominant allele
• Because an allele is dominant does not mean…– it is better, or– it is more common
Polydactyly
recessive allele far more common than dominant only 1 individual out of 500
has more than 5 fingers/toes so 499 out of 500 people are
homozygous recessive (aa)
the allele for >5 fingers/toes is DOMINANT & the allele for 5 digits is recessive
individuals are born with extra fingers or toes
In class assignment
• genetics_xlinked
Homework
• X-Linked Worksheet
Variations on a Human Face
• Variations Lab