Transcript powerpoint notes - Social Circle City Schools

Genetics- the
study of heredity
Heredity- passing
of traits from
parent to offspring
What is it all about?
Genetics
Vocab- Silent walk
 Around
the room there are posters with
words. If you know the word place a
sticker with your name on it on the board.
Write next to the sticker the definition,
explanation or significance of the word.
 Chromatin
Molecules
Mitosis
 Chromosomes
Interphase
 Atoms
Cell Cycle
Why Are Cells So Small?
 Describe
what would happen if the basket
ball court was the size of a football field?
Or a store is 4 times bigger in size without
changing the amount of products in the
store.
Cell Size Limitations
 Just
like a game played on too big a field
or a store that has too much space cells
have limitations on size to maximize
function.
 Most cells are smaller than the . at the end
of this sentence.
 WHY?
Surface Area to Volume Ratio
 BECAUSE:
Maintain Functions!
 Surface area is the area covered by a
membrane
 Volume is the space a cell takes up by the
organelles and cytoplasm
 What happens to the ratio of SA to V as a
cell increases or decreases?
 Potato lab
What happened?
 If
volume increases faster than surface
area there is too much space inside to
move waste out and food in.
 Ex. Diffusion, endocytosis and exocytosis
 Also cellular communication doesn’t reach
organelles fast enough
 Example protein signal can’t find ribosome
in time.
The Cell Cycle
 Once
a cell reaches a certain size it must
stop growing or divide.
 The Cell Cycle (eukaryotes)
 3 phases
 Interphase
Mitosis
Cytokinesis
Cell Cycle
Cell Cycle- Interphase
 This
is the phase where:
*growth occurs
*carry out of normal functions
*copy of DNA
*Prepare for division
3 phases of Interphase
 G1-
right after division, prepares to
replicate DNA
 Some cells stay here and that is the end of
the cycle
 Examples: muscle and nerve cells
3 phases of Interphase
S
phase- copy of DNA is made as
chromatin (relaxed DNA) condenses into
chromosomes to be used for division
3 phases of Interphase
 G2-
prepares to divide nucleus as it takes
inventory
 Proteins to make microtubles is
synthesized in the ribosomes
Cell Cycle- Stage 2
Mitosis
 Nuclear
material divides to separate ends
of the cell
 New cell is formed after cytokinesis
Mitosis and Cytokinesis
The Details!
Stem Cells stem
Know
Want to Know
Learned
How does Mitosis Relate?
 Read
page 258 (Biology and Society)
 With a partner answer the following:
 1. How can stem cells be used?
 2. Describe how stem cells aid in curing
paralysis.
 3. Do you agree or disagree with the use
of stem cells? Why or why not?
How does Mitosis relate?
Stage 2 of Cell Cycle
 Mitosis
is the replication of a cell making
an exact copy of the original. How does
this relate to stem cells?
 What
are the stages of Mitosis?
IPMAT
interphase 1st part of cell cycle
 Mitosis moves to PMAT
 P- prophase
 Location: nucleus and poles of cell
 Purpose: condense chromatin into
chromosomes, form spindle between
poles, nucleolus disappears, centrioles in
animals move to poles, attach spindle to
sister chromatinds.
 I-
What is a chromosome?
 Chromosomes
are the condensed version
of all genetic information.
M
 M-
metaphase
 Location: spindle fibers in middle of cell
 Purpose: motor proteins pull sister
chromatids to middle (equator) of the cell
on the spindle apparatus. Short lived
process.
A
 A-
anaphase
 Location: spindle fibers
 Purpose: sister chromatids are separated
T
 T-
Telophase
 Location: poles or opposite ends of cell
 Purpose: sister chromatids arrive at poles
and start to relax and decondense as the
nucleolus reforms
What has happened?
 What
does mitosis accomplish?
 Are we done yet?
Nope ….Gotta Split!
 Last
stage of the cell cycle
 Cytokinesis- division of cells
Animals
Plants
Prokaryotes
Use
microfilaments to
pinch cytoplasm
in half forming 2
new cells –exact
copies
Form a cell plate
with no pinching
of cytoplasm to
make a rigid layer
fission
Mitosis live… .How long does it
take?
 Mitosis
Who’s in charge of this?
 What
regulates this process?
 When does it know to start? Finish?
 Answer:
 Proteins and enzymes!!!! Like a key
signals a car to start. Each key is set for a
specific car. Most cells know if something
is wrong and will self destroy or will kill
cells not needed: APOPTOSIS
(programmed cell death)
BUT WHAT IF…..
 What
if a cell that has something wrong
with it slips through the cracks?
 Cancer- uncontrolled growth of mutated
cells.
 Example:
And then…..yes it does
Carcinogens
 Carcinogens
are cancer causing agents.
 Examples: Sun exposure, tobacco, drugs,
alcohol, food additives.
 Articles: nanoparticles
 your food
 Lab:
Comparing Sunscreens. Page 255
So how do we know all of
this?intro
vocab
 Gene
Genetics Law of segregation
 Homologous chromosomes
allele
 Gamete
dominant
hybrid
 Haploid
recessive Law of indep Assort
 Fertilization
homozygous
 Diploid
heterozygous
 Meiosis
genotype
 Crossing over
phenotype
Inventory of Your Traits
 Are
you really that special?
 Trait activity.
 Graph on large paper.
Gregor MendelThe Father of Genetics





Austrian monk lived in a monastery
in charge of the garden.
Noticed that some plants were tall,
some were short, etc.
Wanted to find out how 2 tall
plants could produce a short plant
and vice versa.
Begin experimenting with pea plants
Why did pea plants produce the same
seeds every generation?
The Work of Gregor Mendel
 Used

pea plants b/c:
Had a lot of traits to study and produced
offspring fast also could self pollinate or cross
pollinate.
 The
original pair ofOri
plants that were
crossed were called the P (parental)
generation. One tall and one short.
 The offspring of this cross were called the
F1 (first filial) generation. Resulted in 2 tall
plants.
 Offspring from the F1 generation produced
the F2 generation. Result in 3 tall and 1
short.
Where did the short plant come from????
 He repeated with pea types
(green/yellow) and other traits.
Results from Mendel’s Experiment
 Principle
of Dominance: some
alleles are dominant and some
are recessive.
 If dominant is present, it will mask
the recessive allele.
Genes and Alleles
 Genes:
chemical factors that determine a
trait (characteristic).
 Allele: different forms or ways of
expressing a gene.

Ex: AA, Aa, aa
 Dominant
Allele: the trait that always
shows physically and is represented by a
CAPITAL letter.

Ex: AA or Aa
 Recessive
Allele: only shows if the
dominant allele is not present.

Ex: aa
Homozygous (same) vs.
Heterozygous (different)
 Homozygous
or Purebreed: 2 identical
alleles.

Ex: AA= homozygous dominant
aa= homozygous recessive
 Heterozygous
or Hybrid: 2 different
alleles.

Ex: Aa= heterozygous (always dominant)
Phenotype vs. Genotype
 Phenotype:
physical characteristics of the
organism (what it actually looks like).

Ex: tall plant or short plant
 Genotype:
genetic make up of the
organism (what the alleles are).

Ex: AA, Aa or aa
Probability and Punnett
Squares
Probabililty
 The
likelihood that a particular event
will occur.

Flip a coin…what is the probablity it will land on
heads? Does your probablility change depending on
how many times you flip the coin?
 Principles
of probability can be used
to PREDICT the outcome of genetic
crosses.

Probability cannot predit the exact or precise outcome of
an event!
What Causes This?
 Sexual
reproduction:
 Segregation: the separation of alleles
during gamete formation.
 All living things reproduce:
 Sexual crosses genes and causes
variation
 Asexual no variation because exact copy
 Meiosis is the key!!!!
Meiosis
Chromosomes carry our characteristics on
them called traits
 Instructions for those traits are written by
the DNA on sections of those
chromosomes producing proteins
 Genes are the sections.
 Each chromosome has hundreds of genes
that determine traits
Homologous Chromosomes
 The
human body cells have 46
chromosomes- 23 from each parent
 Together they are called homologous
chromosomes.
Haploid and Diploid Cells
 How
do we maintain the magic # 46?
 If only mitosis occurs we would always be
the same- no variation.
 Sexual reproduction produces gametes or
sex cells with information from Mom and
Dad that have 23 chromosomes that
combine to make the magic #46!
Haploid to Diploid
Different Species??
Haploids vs Diploids
 Haploid-
half the genetic material from
parent
 Diploid – the combination of two haploids
one from each parent
 How
does a haploid form?
MEIOSIS
MEIOSIS STEPS
1 – IPMAT
 Meiosis 2 PMAT
 The same steps as mitosis only twice
 Meiosis
Meiosis I
 I-
Interphase- metabolic process
replication DNA and synthesis of proteins
 P- Prophase I- replicated chromosomes
and form sister chromtids by SNAPSIS so
that CROSSING OVER occurs. Spindle
forms
 crossing over
 So the copies that made the pair now are
a little different!
Metaphase I
 M-
sister chromatids line up at equator this
time there are two pairs instead of one like
mitosis.
Anaphase I
 A-
the pairs separate 2n goes to n which
moves pairs doesn’t split the sisters up like
mitosis.
Telophase I
 T-
homologous chromosomes reach poles
with only 1 member of original
chromosome represented because of
crossing over. Followed by cytokinesis.
Then we do it again!!!
 We
do the whole thing again without
copying DNA during interphase. Now we
end up with ½ the information and have
formed sperm and egg!
 Ready to combine to make a zygote
during fertilization.
Here it is!!!dance
So now we can predict!
 Now
that we know how the sex cell is
formed we can predict the possibilities of
the genotype and phenotype of offspring
Punnett Square
 Diagram
showing gene combinations that
might result from a genetic cross. 1900
Reginald Punnett created.
 Monohybrid crosses
 Di
hybrid crosses
Punnett Square Practice
 Creature
 Lab
 Practice
worksheets
Exceptions to Mendel’s Principles
 Mendel’s
principles are not laws because
some alleles are neither dominant or
recessive and many traits are controlled
by multiple alleles
Incomplete Dominance
 Incomplete
Dominance: one allele is not
dominant over the other. Offspring results
in a mixture of the two colors.

Example: Red flower (R) is crossed with
white flower (W) to produce a pink flower
(RW).
Example of Incomplete Dominance
Codominance
 Codominance:
both alleles of the genes
contribute to the phenotype of the
organism.

Example: Chicken with black feathers
crossed with white feathered chicken results
in speckled chicken with black and white
feathers.
Codominance
 For
example, red cows crossed with white
will generate roan cows. Roan refers to
cows that have red coats with white
blotches.
Multiple Alleles
 More
than 2 forms of the same gene in a
population
 Blood type is an example of a common
multiple allele trait.


3 different alleles (A, B, & O).
Blood Types can be A, B, AB, O
Blood Types
Punnett Square with Blood Types
Blood Type Testing Lab
 what
is blood typing?
Polygenic Traits
 More
than one gene contributes to the
phenotype.

Ex: range of skin color in humans
 The
current model of skin color is that
there are 3 genes that contribute to skin
color. So there are 6 total alleles, 3 from
the mother and 3 from the father.
Independent Assortment
 Genes
for 2 different traits do not influence
each other’s inheritance- they separate
independently of eachother.

Ex: seed shape does not influence seed
color.
How are new varieties of plants
and animals made?
 Selective
breeding or Artificial Selection:
Making deliberate crosses or matings of
organisms so the offspring will have a desired
characteristic.

Ex: you desire a white flower so you continually
cross the two lightest yellow flowers for years until
you get some that are white.
What is Genetic Engineering?
A
process of inserting new genetic
information into existing cells in order to
modify a specific organism for the purpose
of changing one of its characteristics.

Ex: Flounder fish produces “antifreeze”
protein that prevents ice from forming in its
blood. DNA is identified, removed and
placed into DNA of strawberry to help it be
more resistant to frost.
Video Lesson
 Label
walk
 KWL
 Videofood
 Opinions?
 Year
long project