Download Notes-Cell Cycle MeiosisII

Cell Size, Cell Cycle, Cancer, and Meiosis
Standard #1: Analyze why organisms
undergo the process of cell division. (10.1)
Identify two reasons why a cell’s growth
is limited.
B. As cell’s increase in size, what happens
to the surface area to volume ratio?
C. Explain why the SA to volume ratio is
important to a cell?
D. Create a Venn diagram comparing sexual
and asexual reproduction.
A.
Standard #1 A.)Identify two reasons why a cell’s
growth is limited.
Cell Size Limitations:
 Cell size increase as cell grows, but the
amount of DNA remains the same
 Larger the cell less efficient it is moving
nutrients and wastes across the cell
membrane.
Standard
1 B) As cell’s increase in size, what happens to the
surface area to volume ratio?
1C) Explain why the SA to volume ratio is
important to a cell?
Size limited by ratio of S.A. to volume:
 volume increase more rapidly than S.A. in a
cell
 as cell grows larger, S.A. becomes too small
 can’t get needed materials in or out of cell
efficiently
Standard 1D) Compare sexual and asexual reproduction.
Asexual
Sexual
Who does it?
•Single celled organism
•Prokaryotes-bacteria
•Most plants and animals
•Some single-celled
organisms
How?
•Binary fission
•Budding
•Meiosis-fertilization of sex
cells
Parents?
•One parent cell
•Needs two different parent
cells (sperm and egg)
Offspring?
•Identical to parent
•Exact clone
•Offspring similar to parents
in kind, but may have
different traits
Advantages
•Increase in numbers
quickly
•Provides genetic diversity
Disadvantages
•Lack of genetic diversity
•Long time it takes for grow
and development
•Longer time to find a mate,
grow, and development of
offspring (seasonal changes)
Standard #2
Explain the Events of the Cell Cycle (10.2 & 10.3)
A.
B.
C.

D.
E.
Draw and label the structure and function of
chromosomes .
Explain why cells divide.
Create a wheel that differentiates between
interphase (G1, S, and G2) and mitosis (P,
M, A, and T) by creating a diagram.
Describe the events that occur during the stages of mitosis and
cytokinesis.
Create a Venn diagram comparing and
contrasting cell division in plant and animal
cells.
Explain the difference between cancerous
and non-cancerous cells.
2 A)Explain the structure and
function of chromosomes .
Chromosome Structure:
 single DNA molecule
wrapped around proteins
(histones)
 maintain shape and aid in
tight packing of DNA


long and threadlike in
nondividing cell
(chromatin)
tightly coiled during cell
division (condensed chromosome)
Chromosome Types and Numbers

each species has certain # in
each cell
 many species have same #


sex chromosomes (X and Y)
 determine sex, carry some genes
 XX normal female, XY normal
male
autosomes - all other
chromosomes
 (44 in humans)
 carry most of the genes

every somatic (body) cell has
2 of each autosome (one from
each parent)
 homologous chromosomes –
 identical chromosomes (size, shape,
genes for same traits)
karotype - photomicrograph
of chromosomes arranged
in pairs
 Diploid (2n) - cell has pairs
(2 of each kind) of
chromosomes

 all somatic cells
 humans: 2n = 46

haploid (monoploid) (n) cell has half the total # of
chromosomes (one of each
kind)
 gametes (reproductive cells) –
 sperm and egg
 humans: n = 23
2B)Explain why cells divide.





For an organism:
To grow
To Repair cells
To create new cells
To decrease the surface area to volume
ratio
2C)Explain the process of the cell
cycle
The Cell Cycle
 Interphase
 G1,S,G2

Mitosis





Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
G0
Interphase







cells spend most of their life in this phase
period between cell divisions - normal cell
activities occurring
G1 phase
 time between cell division and DNA replication
 cells grow to mature size
S phase
 replication (copying) of DNA (chromatin)
G2 phase
 time between DNA replication and cell division
 cell prepares for cell division
Gº phase
 cell exits cell cycle
 no DNA replication, no preparation for cell division
 fully developed cells of CNS (Central Nervous System) stop
dividing at maturity and normally never divide again
why a Gº phase?
 most organisms can’t grow indefinitely
 most cells can reenter cycle to replace dead or damaged cells
when needed
Mitosis
division of nuclear material preceding cell
division
 DNA (chromatin) shortens, tightly coils
and forms visible chromosomes

Prophase
two copies of each chromosome, called
chromatids, are connected by a
centromere
 nucleolus and nuclear membrane break
down and disappear
 centrosomes appear and contain 2
centrioles

 no centrioles in plants
Prophase


centrosomes migrate to opposite poles
spindle fibers radiate from centrosomes
(all fibers form mitotic spindle)
 kinetochore fibers attach to kinetochore (diskshaped protein) of centromere of each chromatid
 extends from each chromatid to centrosome
 polar fibers extend from centrosome to centrosome
Metaphase
kinetochore fibers move chromosomes to
center (equator) of cell
 held in place by those fibers

Anaphase

centromeres divide, chromatids of each
chromosome move toward opposite poles
 kinetochore fibers move them

each chromatid now considered an
individual chromosome
Telophase/Cytokinesis



chromosomes reach the poles
spindle fibers disassemble
chromosomes revert to
chromatin
 less coiled



nuclear membrane reforms
nucleolus reforms
cytokinesis - cytoplasm of
cell divides
 animal -
 cell membrane pinches at cleavage
furrow and two separate cells formed
 plant –
 cell plate forms down middle of cell
End Result of the Cell Cycle





2 equal cells
half the size of original
exact same number chromosomes
exact same kind of chromosomes
http://www.youtube.com/watch?v=EBNvTzNLc0s
2D)Compare plant and animal
cell division
PLANT
ANIMAL
Cell Wall
Centrioles
Square
Circular
Cell plate
Cleavage furrow
Regulating Cell Cycle

Scientist found a signal that regulates cell
cycle:
 Time to divide
 Duplicate their chromosomes
 Enter next phase

Proteins that regulate the cell cycle
 Cyclins
 Regulator proteins
 Internal
 External
Regulating Cell Cycle

Internal regulators

External regulators
 Respond to events inside the cell
 Regulate if a cell can enter mitosis- only if the
chromosomes have been replicated
 Respond to events outside the cell
 Growth factors
 Stimulate the growth and division of cells
 Important for embryonic development and wound
healing
 Other regulatory proteins have opposite effects
 Slow down or stop cell cycle
 Prevents cell growth
 Keeps body tissue from disrupting one another
Apoptosis

Cells die in 2 ways
 Damage or injury
 Programmed death
(Apoptosis)
2E) Explain the difference between
cancerous and non-cancerous cells.
Cancer:
 Body cells lose the
ability to control
cell growth
 Cancer cells do
not:
 Respond to signals
that regulate the
growth of most cells
 Cells divide
uncontrollably
Tumors



abnormal spread of cells due to abnormal cell division
 benign –
 remain within a mass
 no problem unless grow and compress vital organ (fibroid
cysts, warts)
 malignant –
 uncontrolled division of cells that invade and destroy
healthy tissue elsewhere in body (cancer)
metastasis –
 spread of cancer cells beyond original site  break away from tumor and invade other tissues
Cancer Tumor Video
Types of Cancer

Carcinomas –

Sarcomas –

Lymphomas –
 grow in skin and tissues
lining organs of body
 lung and breast
 grow in bone and muscle
tissue
 grow in tissues forming
blood cells
 leukemia - uncontrolled
production of WBC’s
Causes of Cancer

normal cell division caused by genes that
code for growth factors that ensure events
of cell division happen in correct sequence
and rate
 mutations alter expression of these genes
 some spontaneous
Causes of Cancer

carcinogen

some have genetic
predisposition
 substance that increases risk of
cancer
 tobacco, asbestos, ionizing radiation
 X-rays or UV light
 most are mutagens (cause mutations)
 number of exposures to carcinogen
and amount of it


mutations in gamete cells
important to offspring (will
affect the gamete)
Viruses can alter a cell’s DNA to cause
mutation can lead to cancer
 HPV
Treatments


Surgery- removing the cancerous tumor
Targeted beams of radiation

Chemotherapy

Alternative:
 Expose the tumor to radiation
 Chemical compound that kills cancer cells
 Can slow the growth of cancer cells
 Vaccine treatment
 Holistic treatment
 Acupuncture
Standard #3:
Describe how cells can specialize to form a complex multicellular
organism (10.4)
What happens during differentiation?
What are STEM cells and why are they
important?
C. Compare embryonic and adult stem
cells.
D. Explain the advantages and
disadvantages relating to STEM cell
research.
A.
B.
3.A)What happens during differentiation?
Differentiation:
 Fertilized egg (egg +
Sperm) will develop into
an embryo
 Process by which cells
become specialized
 During development an
organism cans can
differentiate into many
types
 Each cell performs a
different task
3.B)What are STEM cells and why are they
important?

Stem cells:

TERMS:
 unspecialized cells that develop into differentiated
cells (cells that have a specific function)
 Totipotent
 Cells that are able to develop into any cell in the body
 Blastocyst




4 days of human development
Hollow balls of cells with a cluster of inner cell mass
Outer cells develop into an attachment to the mother
Inner cells develop into the embryo
 Pluripotent
 Can develop into most cells , but not all body cell types
 These are the inner cell mass of the blastocyst
3.C) Compare embryonic and adult stem cells.
Embryonic Stem Cells
 Pluripotent cells found
in the embryo
 Experiments:
 confirmed that these
cells can form just about
any cell in the human
body
 Formed mouse nerve
cell, muscle cells, and
sperm cells
Adult Stem Cells
 Undifferentiated cells
that are found among
differentiated organs
and tissues
 Cells can differentiate
to renew and replace
cells in the body
 Multipotent cells
 Can develop into many
types of cells, but have
limited potential
3.D) Explain the potential benefits to Stem cell
research.
Using undifferentiated cells to repair or
replace badly damaged cells or tissues
 Examples:

 Heart attacks destroy the heart muscle
 Strokes injure brain cells
 Spinal cord injures cause paralysis-breaks
connections between nerve cells

Many hope to see these examples fixed
using stem cells
3.D) Explain the ethical issues to Stem cell
research.

Adult Stem cells

Embryonic Stem Cells
 Very little ethical questions
 Because it comes from a willing
donor
 Harvesting the embryonic stem
cells kills the embryo
 Ethical issues- life and death
 In distant future there might be a
way to remove the cells without
damaging the embryo
 Other experiments have shown:
 Possible to switch “ON” a small
number of genes to reprogram
adult cells to look and function like
pluripotent embryonic stem cells .
Standard 4
Explain the Importance of Meiosis (11.4)
Explain the steps of meiosis
Compare and contrast cell cycle and
meiosis.
 Explain how meiosis increases genetic
diversity (i.e. crossing over, male vs.
female, etc.).
 Explain how errors in Meiosis result in
chromosome abnormalities.


What is Meiosis?
A.
B.
C.
The division of
body cells.
The formation of
two lung cells
from one lung
cell.
The formation of
sex cells.
0%
A.
0%
B.
0%
C.
Why is Meiosis important?
A.
B.
C.
D.
E.
F.
It keeps the
chromosome number
constant from one
generation to the next
Provides genetic
variation.
Creates gamete cells
Answers A and B
Answers A,B,& C
None of these
0%
0%
0%
0%
0%
0%
A.
B.
C.
D.
E.
F.
How many division(s) do or
does meiosis have?
A.
B.
C.
D.
E.
One
Two
Three
Four
Five
0%
A.
0%
0%
B.
C.
0%
0%
D.
E.
What happens to the chromosome number
after an organism has gone through
meiosis?
A.
B.
C.
The chromosome
number remains
the same.
The chromosome
number doubles.
The chromosome
number is half the
original.
33%
A.
33%
B.
33%
C.
How can your sibling(s) and
you look so different ?
A.
B.
C.
D.
Different parents
Different
chromosomes
donated from
parents
Chromosomes
exchanged
information
All of the above
25%
A.
25%
25%
B.
C.
25%
D.
What type of cells do or does
meiosis produce?
A.
B.
C.
D.
E.
F.
G.
Sperm cells
Egg Cells
Gamete Cells
Somatic cells
Answers A&B
Answers A,B,&C
All of the above
14%
14%
14%
14%
14%
14%
14%
A.
B.
C.
D.
E.
F.
G.
Meiosis creates Only two
identical cells.
50%
A.
B.
50%
True
False
A.
B.
All organisms go through
Meiosis.
50%
A.
B.
50%
True
False
A.
B.
Meiosis
picture:http://images.google.com/imgres?imgurl=genetics.gsk.com/graphics/meiosisbig.gif&imgrefurl=http://genetics.gsk.com/chromosomes.htm&h=482&w=355&prev=/images
%3Fq%3DMeiosis%26svnum%3D10%26hl%3Den%26lr%3D%26ie%3DUTF-8%26sa%3DG
What organisms undergo
Meiosis?

All Eukaryotes that use sexual
reproduction
 Animals –
 examples: humans, cats, dogs
 Plants examples: ferns, flowers
 Some algae examples: red, brown, and green algae
 Most fungi example: yeast
 Some protists example: some paramecium
Why is Meiosis important?


Reduces chromosome number by 1/2
Sexual Reproduction
 fertilization - joining of 2 sex cells (gametes)
 zygote - fertilized egg
Keeps chromosome number constant from
generation to generation
 Provides genetic variation

What are the stages and steps of
Meiosis?




Meiosis I
First division
Has interphase
There are four phases




Prophase I
Metaphase I
Anaphase I
Telophase I and
Cytokinesis I








Meiosis II
Occurs after Meiosis
I
No DNA replication
No interphase
Prophase II
Metaphase II
Anaphase II
Telophase II and
Cytokinesis II
Interphase

G1:

S: synthesis

G2:
 Cell grows to mature size
 Cell copies DNA
 Cell prepares for cell division
Picture taken from:
http://home.comcast.net/~llpellegrini/meiosis.html
Prophase I





DNA strands shorten
and coil into
chromosomes
Spindle fibers appear
Nuclear membrane and
nucleolus disappear
Each chromosome lines
up with a homologue.
Homologue- is an
identical chromosome
 A.K.A- Homolog or
homologus

Picture: CD Biology a guide to
the natural world
Synapsis- pairing of
the homologous
chromosomes.
 Each pair is called a
TETRAD
 (2 chromosomes= 4
chromatids)
Prophase I  Chromatids within their
homologous pair may
tangle up and exchange
portions of their chromatid
 Causes crossing over and the
exchange of genes
 produces a new combo of genes
called genetic recombination
Picture:http://meiosisinfo.wikispaces.com
/
http://www.sci.sdsu.edu/class/bio100/Lectures/Lect05/Image182.g
if
Metaphase I

tetrads randomly
line up at equator

spindle fibers
from one pole
attach to
chromatids of one
homolog

fibers from other
pole attach to
other homolog
Picture: CD Biology a guide to the natural
world
Anaphase I




Tetrads (homologous
chromosomes) separate and
move to opposite poles
Centromeres don’t divide
Each chromosome is still
composed of two chromatids
attached by a centromere
Independent assortment random separation of the
homologous chromosomes
 maternal and paternal
chromosomes randomly
separated (genetic
recombination)
 Increases genetic variation
Picture:
http://meiosisinfo.wikispaces.com/file/view/meana1.gif/219727282/430x184/m
Telophase I And Cytokinesis I




chromosomes reach poles
cytokinesis
2 haploid cells but cell still contains 2 copies of
each chromosome
some species form nuclear membrane, some
don’t
Picture:
http://meiosisinfo.wikispaces.com/file/view/meana1.gif/219727282/430x184/meana1.gif
Meiosis II
Picture:http://images.tutorvista.com/content/cell-reproduction/meiosisii-stage.jpeg
Prophase II


Spindle fibers form
Chromosomes begin to move toward the
center of cell
Picture:http://www.uic.edu/classes/bios/bios100/lecturesf04am/prophase2m.jpg
Metaphase II

Chromosomes move
to the center of the
cell

Each chromosome is
made of two
chromatids held
together by a
centromere
Picture: http://www.uic.edu/classes/bios/bios100/lecturesf04am/metaphase2m.jpg
Anaphase II

Each chromatid separates and moves
toward the opposite poles of the cell.
Picture:http://www.uic.edu/classes/bios/bios100/lecturesf04am/anaphase2m.jpg
Telophase II and Cyotkinesis II



Nuclear membrane
forms around the
chromosomes in each
of the 4 new cells
Cytoplasm divides
(cytokinesis)
Each new cell has half
the number of
chromosomes
compared to the
original.
Picture: http://www.uic.edu/classes/bios/bios100/lecturesf04am/telophase2m.jpg
Mitosis VS. Meiosis
Chart:
Spermatogenesis:
Happens in testes in males
Primary
Spermatocyte
(2n)
Meiosis I
Secondary
Spermatocyte
(n)
Secondary
Spermatocyte
(n)
Meiosis II
Spermatids (n)
Spermatids (n)
Spermatids (n)
Develops into a
mature
Develops into a
mature
Develops into a
mature
sperm cell
sperm cell
sperm cell
Spermatids (n)
Develops into a
mature
sperm cell
Oogenesis:
Happens in the ovaries in females
Primary Oocyte
(2n)
Meiosis I
Polar
Body
Unequal
Division
Secondary Oocyte
(n)
divides
Meiosis II
Ovum (n)
Polar
Body
survives
#1
Unequal Division
Polar
Body
Polar
Body
#2
#3
All 3 Polar Bodies
degenerate
Spermatogenesis and Oogenesis

Males:

Females:
 4 sperm (equal
size)
 23 chromosomeshaploid
 One egg (has all
the cytoplasm and
organelles)
 23 chromosomeshaploid
 Three polar bodies
(degenerate)
Picture:
Picture:https://onlinecourses.science.psu.edu/bio177/sites/onlinecourses.science.psu.edu.bio177/files/u5/Spermatogenesis%20and%2
4.D)Explain how errors in Meiosis result in
chromosome abnormalities.
Nondisjunction disorders
 is the failure of chromosome pairs
to separate properly
during meiosis stage 1 or stage 2
 monosomy
 45 chromosomes in zygote (one copy of
a particular chromosome)

trisomy

Down syndrome

Turner syndrome

Klinefelter syndrome

Super female

XYY (males)
 47 chromosomes in zygote (three copies
of a particular chromosome)
 47 chromosomes (trisomy #21)both
sexes
 45 chromosomes (XO) - females

47 chromosomes (XXY) - males
 47 chromosomes (trisomy of X) (XXX)
What is Meiosis?
A.
B.
C.
The division of
body cells.
The formation of
two lung cells
from one lung
cell.
The formation of
sex cells.
0%
A.
0%
B.
0%
C.
Why is Meiosis important?
A.
B.
C.
D.
E.
F.
It keeps the
chromosome number
constant from one
generation to the next
Provides genetic
variation.
Creates gamete cells
Answers A and B
Answers A,B,& C
None of these
17%
A.
17%
17%
17%
B.
C.
D.
17%
E.
17%
F.
How many division(s) do or
does meiosis have?
A.
B.
C.
D.
E.
One
Two
Three
Four
Five
0%
A.
0%
0%
B.
C.
0%
0%
D.
E.
What happens to the chromosome number
after an organism has gone through
meiosis?
A.
B.
C.
The chromosome
number remains
the same.
The chromosome
number doubles.
The chromosome
number is half the
original.
33%
A.
33%
B.
33%
C.
How can your sibling(s) and
you look so different ?
A.
B.
C.
D.
Different parents
Different
chromosomes
donated from
parents
Chromosomes
exchanged
information
All of the above
25%
A.
25%
25%
B.
C.
25%
D.
What type of cells do or does
meiosis produce?
A.
B.
C.
D.
E.
F.
G.
Sperm cells
Egg Cells
Gamete Cells
Somatic cells
Answers A&B
Answers A,B,&C
All of the above
14%
14%
14%
14%
14%
14%
14%
A.
B.
C.
D.
E.
F.
G.
Meiosis creates Only two
identical cells.
50%
A.
B.
50%
True
False
A.
B.
All organisms go through
Meiosis.
50%
A.
B.
50%
True
False
A.
B.