Cell Reproduction and the Cell Cycle
Cell Reproduction/Cell Cycle
DNA
•
DNA
deoxyribonucleic acid
–
a long, thin molecule that contains info to make
proteins
•
DNA is organized into genes
•
Genes
is a segment of DNA that transmits
information from parent to offspring
–
Genes code for proteins
•
Proteins determine traits
Chromosomes
•
Chromosome
tightly-coiled
DNA.
•
Chromatid
a copy of a
chromosome
–
Called sister chromatids if two are
attached
•
Centromere
protein that
attaches two sister chromatids
Chromosomes
•
The DNA in eukaryotic cells wraps around
proteins called
histones
.
–
They aid in shaping and maintaining the tight
packing of DNA
I.
Prokaryotic Cell Cycle
A.
Bacterial cells contain single, simple, circular
strands of “naked” DNA.
B.
Binary Fission- asexual reproduction of
prokaryotic cells.
•
Steps to Binary Fission
1.
COPY
DNA
2.
DNA
SLIDES
to opposite sides of the cell
3.
Cell
SPLITS
–
Cell membrane pinches in creating 2 identical cells.
Binary Fission
CELL CYCLE for Eukaryotic Cells
Overview
Life cycle of a cell that begins when a cell is formed and
ends when it divides.
G
1
normal growth/ life of cell
-majority of cell life.
S
DNA is copied (Synthesis of DNA)
G
2
Organelles are replicated
-cell is prepared for nucleus to divide
M
Mitosis- nuclear division
C
Cytokinesis- cytoplasm divides (forms 2 new cells)
HW Questions
Answer in complete sentences.
•
In binary fission, how does the offspring’s
genes compare to the parent’s genes?
Explain
.
•
Using your knowledge of prokaryotic and
eukaryotic cells,
why
do you think the
eukaryotic cell cycle is longer/has more steps
than the prokaryotic cell cycle?
II. Eukaryotic Cell Cycle
A.
Interphase –
normal growth phase of the
cell.
- the majority of the cell cycle is spent in
interphase
1.
G
1
phase-
growth of the cell immediately
following cell division
2.
S phase-
DNA replication
3.
G
2
phase-
Replication of organelles, cell
enlarges
•
Cells that don’t reproduce don’t have an S or
G
2
phase. (ex. Red blood cells)
•
Genetic material is in loose tangles of DNA
and associated proteins (
Histones)
called
Chromatin.
•
Chromatin is invisible to most light
microscopes.
B.
Mitosis
- the production of 2 new, identical nuclei.
1.
Prophase
(pairing)
a. Chromatin coils to form thick, compact
structures called
Chromosomes.
b.
Sister chromatids are paired in a chromosome
(two identical copies of DNA held together by a
centromere)
c. Nuclear membrane breaks down
d.
Centrosomes
(bundles of microtubules) begin to
move to opposite sides of the cell.
-Spindle fibers
extend from the
centrioles (part of centrosome) across the
cell
Chromosome
Prophase
2.
Metaphase
(midline)
a. Spindles attach to the centromeres of each
chromosome.
b.
Chromosomes are pulled to the equator of
the cell forming a line.
3.
Anaphase
(away)
a
. Centromeres are split and sister
chromatids are pulled towards opposite sides
of the cell.
** At this point each chromatid is now called a
Chromosome.
4.
Telophase
(two nuclei)
a. Identical chromosomes sets reach opposite
sides of the cell.
b. Spindle fibers break down.
c.
Two new nuclear membranes begin to
form around the chromosome sets.
d. Chromosomes begin to uncoil into
chromatin.
** This ends mitosis, but not the cell cycle.
Telophase
C.
Cytokinesis- the splitting of the cytoplasm
into two identical daughter cells.
- In animal cells, the cell membrane is pinched
in creating a
cleavage furrow
.
- In plant cells, secretion vesicles form a
cell
plate
between the chromosome sets splitting
the cell membrane and cell wall.
- Vesicles come from the Golgi
***After cytokinesis, each new cell
immediately begins the G
1
phase of Interphase.
Mitosis Rap
•
https://www.youtube.com/watch?v=pOsAbTi
9tHw
Animal cell mitosis
1
2
3
6
5
4
8
7
9
10
11
12
Plant cell mitosis
III. Meiosis
A.
Homologous chromosomes-
A.
matching pairs of chromosomes that are the
same size, shape and code
for the same
hereditary traits
B.
BUT
may NOT be
exactly alike.
Chromosome Types
•
Sex chromosomes
– are chromosomes that
determine the gender of an organism.
–
XX – female
•
(mom gives X, dad gives X)
–
XY – male
•
(mom gives X, dad gives Y)
•
Autosomes
– All the other chromosomes
other than the sex chromosomes.
Chromosomes
•
Humans have two sex chromosomes
–
One from mother
–
One from father
•
Human # Sex Chromosomes
–
1 pair
2 chromosomes
Human Chromosome Number
•
Humans have two copies of each autosome.
–
One set from mother
–
One set from father
•
Human # Autosomes
–
22 pair
44 chromosomes
•
Total #= 23 pair
46 chromosomes
1.
Diploid (2n) cells-
contain a full set of
homologous pairs
- 1 set from mother
- 1 set from father
a.
Diploid #
is the total # of chromosomes in a
normal body cell.
ex. Human diploid # is 46
2.
Haploid (n) cells-
contain a half set of
homologous pairs
-(one copy from either mother or father)
a.
Haploid #
is half of the diploid #.
ex. Human haploid # is 23
b.
Gametes
(sex cells) are haploid.
- male sperm (from father)
- female egg (from mother)
- fusion of egg and sperm produces a
diploid (2n) cell called a
zygote
How are gametes (the sperm and egg)
made?
•
Meiosis
–
production of haploid gametes (sex cells)
Process of Meiosis
•
Interphase occurs normally
–
G1
–
S
–
G2
•
Goal of meiosis is similar to mitosis
–
now the goal is production of haploid cells (instead of
diploid)
•
There are two rounds of division in meiosis
–
Split into Meiosis I and Meiosis II
–
Phase names are the same (Pro-, Meta-, Ana-, Telo-)
B.
Meiosis I
1.
Prophase I
a. Chromatin coils to form chromosomes.
b. Nucleus disappears
Special to Meiosis I:
c. Homologous chromosomes pair up to form
tetrads.
d. The chromatid arms of the homologous
pairs can become intermingled and exchange
genetic material. (
Crossing Over)
- The random exchange of genes caused by
crossing over creates chromosomes w/ a unique
combination of genes. (
Genetic Recombination)
2.
Metaphase I
a.
Homologous pairs of chromosomes
line
up at the equator of the cell. (one on each
side)
-Homologous chromosomes
are
randomly lined up on midline.
(
Independent Assortment)
b. Spindle fibers attach to the
centromeres.
When gametes combine, offspring show variation due to
independent assortment and crossing over
3.
Anaphase I
- Half of the chromosomes are pulled in
one direction; other half pulled in opposite
direction
-
Centromeres are not broken, sister
chromatids remain attached
- Chromosome number is reduced from
diploid(2n) to haploid(n).
4.
Telophase I/ Cytokinesis
a. New nuclei may or may not form.
b. Cell splits into two haploid cells (
not
genetically identical).
C. Meiosis II
- Similar steps to mitosis, but w/ haploid cells.
1.
Prophase II
- sister chromatids are paired, centrioles migrate to
opposite sides of cell
2.
Metaphase II
- Chromosomes line up on midline
3.
Anaphase II
- Sister chromatids are separated
4.
Telophase II
/ Cytokinesis –
-form nuclear membranes around chromosomes
-produces
4 genetically different, haploid gametes:
-
Males
produce 4 functional sperm.
-
Females
- only one cell becomes egg
- other 3 are non-functional gametes (called
polar bodies)
http://highered.mcgraw-
hill.com/sites/0072495855/student_view0/chapter28/animation__
how_meiosis_works.html
•
Turn in homework from yesterday (if you
haven’t already)
•
Answer the “Check for Understanding”
questions on page 11 of the notes
Key points of Meiosis
●
The process results in 4 daughter cells
●
Daughter cells are haploid (n)
●
Daughter cells have unique combinations of
chromosomes
Meiosis creates gametes
(sperm and eggs)
Meiosis ensures variability in
offspring
Gametes combine to create a
zygote which is diploid (2N) -
process of sexual reproduction
Check for understanding
1. What phase directly follows telophase I?
2. How many cells are present at the end of meiosis I ?
3. A cell has a diploid number of 60, what is the organism's
haploid number?
4. Meiosis forms what type of cells?
5. In what phase do homologous chromosomes pair up and
crossing-over can occur?
6. In what phase do the CHROMATIDS separate?
prophase II
2
30
gametes
prophase 1
anaphase 2
Pg 180
7. Which of these pictures is metaphase I of
MEIOSIS and which is metaphase of MITOSIS?
Mitosis Meiosis
REGULATION OF THE CELL CYCLE
AND CANCER
Control of the Cell Cycle
G1 Checkpoint - Check to see if DNA is damaged
G2 Checkpoint - Check to see if DNA is replicated properly
M Checkpoint - spindle assembly checkpoint, check for alignment of
chromosomes
Apoptosis
- programmed cell death, occurs if any of the checks fail
Mutations Can Cause Cancer
•
Cancer
a term used to indicate a disease characterized
by abnormal cell growth
–
Cancer cells are not like normal cells
•
normal cell growth is a highly regulated process
•
cancer cells do not respond to stop signals for growth so they continue to
divide at fast rates without stopping
•
Video: From a normal cell to a cancer cell
•
Cancer cells that accumulate in an area are called a
tumor
•
Tumors are classified as benign or malignant.
–
A
benign
tumor does not invade surrounding tissues and can be surgically
removed.
–
A
malignant
tumor is very harmful.
»
spreads into other tissues and interferes with organ function.
»
The most devastating property of malignant tumors is that its cells are
able to break free of the tumor and enter the blood and lymph system.
»
Then these cells are carried to new locations in the body and form new
growths
»
the spread of malignant cells beyond their origins is called metastasis.
1. Cancer Genes
•
Cells become cancerous when mutations occur in genes that
regulate cell growth.
•
An example of a growth regulating gene is called the ras gene.
–
The ras gene helps prevent uncontrolled cell division.
–
When there is a mutation in the ras gene, cell division occurs more
rapidly than normal
–
The ras genes are examples of
oncogenes-a gene that when mutated
can cause a cell to become cancerous.
•
It takes time for an individual cell to accumulate the necessary
mutations to cause cancer
–
that is why most cancers occur in people over 40.
Review: Prokaryotic vs. Eukaryotic; Sexual vs. Asexual Reproduction
Explore the process of cell reproduction, DNA structure, chromosomes, and the differences between prokaryotic and eukaryotic cell cycles. Learn about binary fission, mitosis, and cytokinesis in the context of cellular growth and division. Understand the significance of genes, DNA organization into chromosomes, and the intricate steps involved in the cell cycle of eukaryotic cells.
Download Presentation
Please find below an Image/Link to download the presentation.
The content on the website is provided AS IS for your information and personal use only. It may not be sold, licensed, or shared on other websites without obtaining consent from the author. Download presentation by click this link. If you encounter any issues during the download, it is possible that the publisher has removed the file from their server.
E N D
Presentation Transcript
DNA DNA deoxyribonucleic acid a long, thin molecule that contains info to make proteins DNA is organized into genes Genes is a segment of DNA that transmits information from parent to offspring Genes code for proteins Proteins determine traits
Chromosomes Chromosome tightly-coiled DNA. Chromatid a copy of a chromosome Called sister chromatids if two are attached Centromere protein that attaches two sister chromatids
Chromosomes The DNA in eukaryotic cells wraps around proteins called histones. They aid in shaping and maintaining the tight packing of DNA
I. Prokaryotic Cell Cycle A. Bacterial cells contain single, simple, circular strands of naked DNA. B. Binary Fission- asexual reproduction of prokaryotic cells. Steps to Binary Fission 1. COPY DNA 2. DNA SLIDES to opposite sides of the cell 3. Cell SPLITS Cell membrane pinches in creating 2 identical cells.
CELL CYCLE for Eukaryotic Cells Overview Life cycle of a cell that begins when a cell is formed and ends when it divides. G1 normal growth/ life of cell -majority of cell life. S DNA is copied (Synthesis of DNA) G2 Organelles are replicated -cell is prepared for nucleus to divide M Mitosis- nuclear division C Cytokinesis- cytoplasm divides (forms 2 new cells)
HW Questions Answer in complete sentences. In binary fission, how does the offspring s genes compare to the parent s genes? Explain. Using your knowledge of prokaryotic and eukaryotic cells, why do you think the eukaryotic cell cycle is longer/has more steps than the prokaryotic cell cycle?
II. Eukaryotic Cell Cycle A. Interphase normal growth phase of the cell. - the majority of the cell cycle is spent in interphase 1. G1 phase- growth of the cell immediately following cell division 2. S phase- DNA replication 3. G2phase- Replication of organelles, cell enlarges
Cells that dont reproduce dont have an S or G2phase. (ex. Red blood cells) Genetic material is in loose tangles of DNA and associated proteins (Histones) called Chromatin. Chromatin is invisible to most light microscopes.
B. Mitosis- the production of 2 new, identical nuclei. 1. Prophase (pairing) a. Chromatin coils to form thick, compact structures called Chromosomes. b. Sister chromatids are paired in a chromosome (two identical copies of DNA held together by a centromere) c. Nuclear membrane breaks down d. Centrosomes (bundles of microtubules) begin to move to opposite sides of the cell. -Spindle fibers extend from the centrioles (part of centrosome) across the cell
2. Metaphase (midline) a. Spindles attach to the centromeres of each chromosome. b. Chromosomes are pulled to the equator of the cell forming a line.
3. Anaphase (away) a. Centromeres are split and sister chromatids are pulled towards opposite sides of the cell. ** At this point each chromatid is now called a Chromosome.
4. Telophase (two nuclei) a. Identical chromosomes sets reach opposite sides of the cell. b. Spindle fibers break down. c. Two new nuclear membranes begin to form around the chromosome sets. d. Chromosomes begin to uncoil into chromatin. ** This ends mitosis, but not the cell cycle.
C. Cytokinesis- the splitting of the cytoplasm into two identical daughter cells. - In animal cells, the cell membrane is pinched in creating a cleavage furrow. - In plant cells, secretion vesicles form a cell plate between the chromosome sets splitting the cell membrane and cell wall. - Vesicles come from the Golgi
***After cytokinesis, each new cell immediately begins the G1 phase of Interphase.
Mitosis Rap https://www.youtube.com/watch?v=pOsAbTi 9tHw
Animal cell mitosis 4 2 6 1 3 5 7 9 11 10 12 8
III. Meiosis A. Homologous chromosomes- A. matching pairs of chromosomes that are the same size, shape and code for the same hereditary traits B. BUT may NOT be exactly alike.
Chromosome Types Sex chromosomes are chromosomes that determine the gender of an organism. XX female (mom gives X, dad gives X) XY male (mom gives X, dad gives Y) Autosomes All the other chromosomes other than the sex chromosomes.
Chromosomes Humans have two sex chromosomes One from mother One from father Human # Sex Chromosomes 1 pair 2 chromosomes
Human Chromosome Number Humans have two copies of each autosome. One set from mother One set from father Human # Autosomes 22 pair 44 chromosomes Total #= 23 pair 46 chromosomes
1. Diploid (2n) cells- contain a full set of homologous pairs - 1 set from mother - 1 set from father a. Diploid # is the total # of chromosomes in a normal body cell. ex. Human diploid # is 46
2. Haploid (n) cells- contain a half set of homologous pairs -(one copy from either mother or father) a. Haploid # is half of the diploid #. ex. Human haploid # is 23 b. Gametes (sex cells) are haploid. - male sperm (from father) - female egg (from mother) - fusion of egg and sperm produces a diploid (2n) cell called a zygote
How are gametes (the sperm and egg) made? Meiosis production of haploid gametes (sex cells)
Process of Meiosis Interphase occurs normally G1 S G2 Goal of meiosis is similar to mitosis now the goal is production of haploid cells (instead of diploid) There are two rounds of division in meiosis Split into Meiosis I and Meiosis II Phase names are the same (Pro-, Meta-, Ana-, Telo-)
B. Meiosis I 1. Prophase I a. Chromatin coils to form chromosomes. b. Nucleus disappears Special to Meiosis I: c. Homologous chromosomes pair up to form tetrads. d. The chromatid arms of the homologous pairs can become intermingled and exchange genetic material. (Crossing Over) - The random exchange of genes caused by crossing over creates chromosomes w/ a unique combination of genes. (Genetic Recombination)
2. Metaphase I a. Homologous pairs of chromosomes line up at the equator of the cell. (one on each side) -Homologous chromosomes are randomly lined up on midline. (Independent Assortment) b. Spindle fibers attach to the centromeres.
When gametes combine, offspring show variation due to independent assortment and crossing over
3. Anaphase I - Half of the chromosomes are pulled in one direction; other half pulled in opposite direction - Centromeres are not broken, sister chromatids remain attached - Chromosome number is reduced from diploid(2n) to haploid(n).
4. Telophase I/ Cytokinesis a. New nuclei may or may not form. b. Cell splits into two haploid cells (not genetically identical).
C. Meiosis II - Similar steps to mitosis, but w/ haploid cells. 1. Prophase II- sister chromatids are paired, centrioles migrate to opposite sides of cell 2. Metaphase II- Chromosomes line up on midline 3. Anaphase II- Sister chromatids are separated 4. Telophase II / Cytokinesis -form nuclear membranes around chromosomes -produces 4 genetically different, haploid gametes: -Males produce 4 functional sperm. -Females- only one cell becomes egg - other 3 are non-functional gametes (called polar bodies) http://highered.mcgraw- hill.com/sites/0072495855/student_view0/chapter28/animation__
Turn in homework from yesterday (if you haven t already) Answer the Check for Understanding questions on page 11 of the notes
Key points of Meiosis The process results in 4 daughter cells Daughter cells are haploid (n) Daughter cells have unique combinations of chromosomes
Meiosis creates gametes (sperm and eggs) Meiosis ensures variability in offspring Gametes combine to create a zygote which is diploid (2N) - process of sexual reproduction
Check for understanding 1. What phase directly follows telophase I? prophase II 2. How many cells are present at the end of meiosis I ? 2 3. A cell has a diploid number of 60, what is the organism's haploid number? 30 4. Meiosis forms what type of cells? gametes 5. In what phase do homologous chromosomes pair up and crossing-over can occur? prophase 1 6. In what phase do the CHROMATIDS separate? anaphase 2
Pg 180 7. Which of these pictures is metaphase I of MEIOSIS and which is metaphase of MITOSIS? Mitosis Meiosis
