Biology – Chapter 10
Cell Growth and Division
I. Cell Growth, Division, and Reproduction (10.1)
A. Limits to Cell Size
1. Why do cells divide, rather than continue to grow larger?
As a cell becomes larger, the movement of materials
between the cell membrane and the interior becomes
more difficult.
I. Cell Growth, Division, and Reproduction (10.1)
A. Limits to Cell Size
2. How do materials get moved into and out of a cell?
Through the cell membrane
3. SURFACE AREA TO VOLUME RATIO:
As an index, a larger ratio means that the cell has an
easier time moving materials into/out of and within a
cell
I. Cell Growth, Division, and Reproduction (10.1)
A. Limits to Cell Size
4. Express the answer to #1 in terms of surface area and
volume:
As cells grow, the volume increases faster than the
surface area (do you know the formulas for the V and
SA of a sphere?)
I. Cell Growth, Division, and Reproduction (10.1)
B. CELL DIVISION:
Process by which one cell divides into 2 daughter cells
I. Cell Growth, Division, and Reproduction (10.1)
C. CELL DIVISION AND REPRODUCTION
1. ASEXUAL REPRODUCTION:
Production of genetically identical offspring from a
single parent
I. Cell Growth, Division, and Reproduction (10.1)
C. CELL DIVISION AND REPRODUCTION
1a. How do the offspring of asexual reproduction
compare to the parent cell?
Those offspring are genetically identical to the parent
(clones)
I. Cell Growth, Division, and Reproduction (10.1)
C. CELL DIVISION AND REPRODUCTION
1. b. VEGETATIVE PROPAGATION – Asexual reproduction
which enables a plant to produce genetically identical
offspring (runners, tissue-culture, plantlets)
I. Cell Growth, Division, and Reproduction (10.1)
C. CELL DIVISION AND REPRODUCTION
1. c. BUDDING – Asexual reproduction which produces a
more-or-less fully-formed individual (yeast, Hydra)
I. Cell Growth, Division, and Reproduction (10.1)
C. CELL DIVISION AND REPRODUCTION
1. d. Advantages of asexual reproduction:
Speed of reproduction,
(Lack of genetic variation may be an issue)
I. Cell Growth, Division, and Reproduction (10.1)
C. CELL DIVISION AND REPRODUCTION
2. SEXUAL REPRODUCTION:
Fusion of 2 cells to produce a new individual
I. Cell Growth, Division, and Reproduction (10.1)
C. CELL DIVISION AND REPRODUCTION
2. a. How do the offspring of sexual reproduction compare
to their parent cells?
Offspring are genetically different
I. Cell Growth, Division, and Reproduction (10.1)
C. CELL DIVISION AND REPRODUCTION
2. b. Advantages of sexual reproduction:
Genetic diversity; recombination of alleles (forms of genes)
provides for new and different characteristics
II. Process of Cell Division (10.2)
C. CELL DIVISION AND REPRODUCTION
2. b. Advantages of sexual reproduction:
Genetic diversity; recombination of alleles (forms of genes)
provides for new and different characteristics
II. Process of Cell Division (10.2)
A. CHROMOSOME –
“Colored-Body” - Tightly wound DNA Bundles
B. Prokaryotic Chromosome –
Single loop of DNA
C. Eukaryotic Chromosome –
Linear (has ends); multiple chromosomes
1. CHROMATIN –
Lightly twisted DNA/protein combination
DNA is wound around histone proteins
II. Process of Cell Division (10.2)
D. CELL CYCLE –
Repeated events through which cell passes
1. Prokaryotic Cell Cycle –
Growth, DNA replication, Cell Division
a. BINARY FISSION –
Process by which single-celled organisms
produce 2 genetically identical cells
II. Process of Cell Division (10.2)
D. CELL CYCLE
2. Eukaryotic Cell Cycle
a. INTERPHASE –
“In-between” cell division time, period of
normal function and growth; most of cell’s life is
spent in interphase
i. G1: Gap 1; most of cell’s life; period of
growth & normal function
ii. S: Synthesis; DNA replication
iii. G2: Gap 2; shortest interphase part;
organelles for cell division produced
II. Process of Cell Division (10.2)
D. CELL CYCLE
2. Eukaryotic Cell Cycle
b. MITOSIS – Nuclear Division
i. Prophase – Genetic material condenses to
chromosomes, nuclear envelope breaks down,
spindle starts to form
a. CENTROMERE – Attachment point of
chromatids
b. CHROMATID – Identical halves of a
chromosome (they don’t cross like an X)
II. Process of Cell Division (10.2)
D. CELL CYCLE
2. Eukaryotic Cell Cycle
b. MITOSIS (continued)
ii. Metaphase – Centromeres align along center
of cell; spindle fibers attach to centromeres
iii. Anaphase – Chromosomes separate;
chromatids move toward opposite poles
iv. Telophase – Chromatids start to unwind;
nuclear envelope begins to reform
II. Process of Cell Division (10.2)
D. CELL CYCLE
2. Eukaryotic Cell Cycle
c. CYTOKINESIS – Process by which a cell splits into two
daughter cells (division of non-nuclear material)
i. Cytokinesis in Animal Cells: Cell/cytoplasm
pinches into two cells
ii. Cytokinesis in Plant Cells: Celll plate froms along
middle – develops into membranes which then produce
a cell wall
d. What are the results (cell-wise) at the end of
cytokinesis? 2 daughter cells which are genetically
identical
III. Regulating the Cell Cycle (10.3)
A. Make a list of the types of inputs which regulate cell division:
Proximity, wear, trauma,
B. CYCLINS – proteins which regulate the cell cycle
C. Internal Regulators: Keep cell from moving on (in cell cycle) until certain
steps are accomplished
D. External Regulators: Proteins which respond to events outside of the cell
1. GROWTH FACTOR – Chemicals which stimulate cell groth and
division
III. Regulating the Cell Cycle (10.3)
E. APOPTOSIS – Process of programmed cell death
Example: divisions between digits of hands, feet
F. CANCER – Condition where cells don’t respond to signals that
control
cell division (division is uncontrolled)
1. Why do cancer cells not stop dividing?
They do not respond to normal “stop dividing” signals
2. TUMOR – Mass of abnormal cells
3. Causes of Cancer (make a list): Defects (like faulty p53
gene), UV light, smoking, radiation, certain viruses, asbestos,
radon,
IV. Cell Differentiation (10.4)
A. CELL DIFFERENTIATION -
Process by which cells become specialized (in multicellular
organisms)
How many cells did you start as?
How many different types can you identify now?
IV. Cell Differentiation (10.4)
B. A little vocabulary review
1. GAMETE – Haploid sex cell
a. EGG – Female sex cell produced by ovaries
b. SPERM – Male sex cell produced by testes
2. ZYGOTE – Fertilized egg
3. EMBRYO - Developmental stage of a multicellular organism;
differentiation has begun
(somewhere between zygote and fetus)
IV. Cell Differentiation (10.4)
C. Into what sorts of cells does a zygote (fertilized egg) develop?
D. STEM CELL – Unspecialized (undifferentiated) cell which can
develop into more (and different) specialized cell
types
V. Meiosis (11.4, page 323)
A. HOMOLOGOUS – Condition of a matching chromosome from
another parent
(2 homologous chromosomes per pair)
B. DIPLOID – “Two sets” - having 2 sets of chromosomes; one
inherited from each parent *
C. HAPLOID - “One set” – Half the normal amount of genetic
material (this is the genetic complement of a
gamete) **
V. Meiosis (11.4, page 323)
D. Phases of Mitosis Meiosis
1. Meiosis I
a. PROPHASE I – Nuclear envelope breaks down;
chromosomes become visible;
homologous pairs form tetrads
i. TETRAD – Structure of 4 chromatids/2 homologous
chromosomes aligned face-to-face
ii. CROSSING OVER – Exchange of portions of homologous
chromatids – mixes maternal and paternal
DNA; sets up new combinations of genes
V. Meiosis (11.4, page 323)
Typo!
D. Phases of Mitosis Meiosis
1. Meiosis I
b. METAPHASE I – Spindle forms, attaches to each tetrad,
tetrads align along middle of cell
c. ANAPHASE I – Homologs (individual chromosomes, not
chromatids) move toward opposite poles
What is a
homolog?
d. TELOPHASE I – Homologs (chromosomes) cluster, nuclear
envelope reforms
What moves during
anaphase?
V. Meiosis (11.4, page 323)
D. Phases of Mitosis Meiosis
1. Meiosis I
e. CYTOKINESIS – Cell divides
THESE DAUGHTERS ARE NOT GENETICALLY
IDENTICAL!
During oogenesis, the cytokinesis will likely be uneven
1 cell ends up with most of the cytoplasm, the other
nuclear material forms a polar body
V. Meiosis (11.4, page 323)
D. Phases of Mitosis Meiosis
2. Meiosis II
a. PROPHASE II – Nuclear envelope breaks down; homologs
reform, spindle forms
b. METAPHASE II – Homologs (chromosomes) align along
middle
c. ANAPHASE II – Chromatids move toward opposite poles
(like anaphase of mitosis)
d. TELOPHASE II – Chromatids cluster, unwind, nuclear
envelope reforms
e. CYTOKINESIS –Cells divide (uneven division in oocytes, which
produces a second polar body
V. Meiosis (11.4, page 323)
E. What are the results (cell-wise) at the end of Meiosis?
Up to 4 cells which are haploid and no longer genetically identical
Some notes/easy definitions:
* = number chromosomes present at metaphase of mitosis
** = number of chromatids in a gamete