Download PowerPoint Lectures for Biology: Concepts and

Chapter 8
The Cellular Basis of
Reproduction and Inheritance
PowerPoint Lectures for!
Biology: Concepts and Connections, Fifth Edition!
– Campbell, Reece, Taylor, and Simon
Lectures by Chris Romero
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Objective: • a. Recognize the chromosomes of daughter
cells, formed through the processes of
asexual reproduction and mitosis, the
formation of somatic (body) cells in
multicellular organisms, are identical to the
chromosomes of the parent
!
• Reproduction is one phase of an organism's life
cycle!
– Sexual reproduction!
• Fertilization of sperm and egg produces
offspring
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
– Asexual reproduction!
• Offspring are produced by a single parent,
without the participation of sperm and egg!
• Cell division is at the heart of organismal
reproduction
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
CONNECTIONS BETWEEN CELL DIVISION
AND REPRODUCTION
Like begets like, more or less!
• Asexual reproduction!
– Chromosomes are duplicated and cell divides !
– Each daughter cell is genetically identical to
the parent and the other daughter!
• Sexual reproduction!
– Each offspring inherits a unique combination
of genes from both parents!
– Offspring can show great variation
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Cells arise only from preexisting cells!
• 1858 Rudolf Virchow: "Every cell from a cell" !
• This is at the heart of the perpetuation of life !
– Can reproduce an entire unicellular organism!
– Is the basis of sperm and egg formation!
– Allows for development from a single fertilized
egg to an adult organism!
– Functions in an organism's renewal and repair
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Prokaryotes reproduce by binary fission!
• Prokaryotic cells reproduce asexually by a type
of cell division called binary fission!
– Genes are on one circular DNA molecule!
– The cell replicates its single chromosome!
– The chromosome copies move apart!
– The cell elongates!
– The plasma membrane grows inward
(cleaves), dividing the parent into two
daughter cells
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 8-3a
Plasma!
membrane
Prokaryotic!
chromosome
Cell wall
Duplication of chromosome!
and separation of copies
Continued elongation of the !
cell and movement of copies
Division into!
two daughter cells
LE 8-3b
Prokaryotic chromosomes
Colorized TEM 32,500
×
THE EUKARYOTIC CELL CYCLE AND MITOSIS
The large, complex chromosomes of eukaryotes
duplicate with each cell division!
• Eukaryotic genes !
– Many more than in prokaryotes!
– Grouped into multiple chromosomes in the
nucleus
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Eukaryotic chromosomes !
– Contain a very long DNA molecule associated
with proteins!
– Most of the time occur in the form of thin,
loosely packed chromatin fibers!
– Condense into visible chromosomes just
before cell division
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Eukaryotic cell division!
1. Chromosomes replicate!
• Sister chromatids joined together at the
centromere!
2. Sister chromatids separate!
• Now called chromosomes!
3. Cell divides into two daughter cells!
• Each with a complete and identical set of
chromosomes
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Sister chromatids
Centromere
TEM 36,600×
LE 8-4b
LE 8-4c
Chromosome!
duplication
Centromere
Sister !
chromatids
Chromosome!
distribution!
to!
daughter!
cells
The cell cycle multiplies cells!
•
The cell cycle: an ordered series of events
extending from the time a cell is formed until it
divides into two !
•
3 Major processes:!
I.
Interphase!
II.
Mitosis!
III. Cytokinesis
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Most of the time of cell cycle is in interphase!
• 3 Stages:!
– G1: cell grows in size!
– S: DNA synthesis (replication) occurs!
– G2: Cell continues to grow and prepare for
division!
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• The cell actually divides in mitotic (M) phase!
– Mitosis: nuclear division!
– Cytokinesis: cytoplasmic division!
– Duplicated chromosomes evenly distributed
into two daughter nuclei
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 8-5
INTERPHASE
S!
(DNA synthesis)
G1
PH OTIC
AS
!
E(
M)
ito
si
s
C
M
MIT
ne
i
ok
t
y
s
i
s
G2
Cell division is a continuum of dynamic changes!
• Interphase: Duplication of the genetic material
ends when chromosomes begin to become
visible !
• Prophase (the first stage of mitosis): The mitotic
spindle is forming. Centrosomes migrate to
opposite ends of the cell Chromatins completely
coil into chromosomes; nucleoli and nuclear
membrane disperse
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Metaphase: The spindle is fully formed;
chromosomes are aligned single file with
centromeres on the metaphase plate !
• Anaphase: Chromosomes separate from the
centromere, dividing to arrive at poles!
• Telophase: Cell elongation continues, a nuclear
envelope forms around chromosomes,
chromosomes uncoil, and nucleoli reappear!
• Cytokinesis: The cytoplasm divides
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LM 250 ×
LE 8-6a
INTERPHASE
Centrosomes!
(with centriole pairs)
Nucleolus
Chromatin
Nuclear!
Plasma!
envelope! membrane!
PROPHASE
Early mitotic!
spindle
PROPHASE
Centrosome
Chromosome, consisting!
of two sister chromatids!
Centromere!
Fragments!
of nuclear!
envelope
Kinetochore
Spindle !
microtubules!
LE 8-6b
METAPHASE
ANAPHASE
Cleavage!
furrow
Metaphase!
plate
Spindle
TELOPHASE AND CYTOKINESIS
Daughter!
chromosomes
Nuclear!
envelope!
forming
Nucleolus!
forming
Cytokinesis differs for plant and animal cells!
• Animals !
– Ring of microfilaments contracts into cleavage
furrow!
– Cleavage occurs!
• Plants !
– Vesicles fuse into a membranous cell plate !
– Cell plate develops into a new wall between
two daughter cells
Animation: Cytokinesis
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 8-7a
SEM 140×
Cleavage!
furrow
Cleavage furrow
Contracting ring of!
microfilaments
Daughter cells
Cell plate!
forming
Wall of!
parent cell
Daughter!
nucleus
TEM 7,500×
LE 8-7b
Cell wall
Vesicles containing!
cell wall material
New cell wall
Cell plate
Daughter cells
8.8 Anchorage, cell density, and chemical growth
factors affect cell division!
• An organism must be able to control the timing
of cell division!
!
• Anchorage dependence !
– Most animal cells must be in contact with a
solid surface to divide
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Density-dependent inhibition!
– Cells form a single layer!
– Cells stop dividing when they touch one
another!
– Inadequate supply of growth factor causes
division to stop
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 8-8a
Cells anchor to!
dish surface!
and divide.
When cells have!
formed a complete!
single layer, they!
stop dividing!
(density-dependent!
Inhibition).
If some cells are!
scraped away, the!
remaining cells!
divide to fill the dish!
with a single layer!
and then stop!
(density-dependent!
inhibition).
LE 8-8b
After forming a!
single layer,!
cells have!
stopped dividing.
Providing an!
additional supply of!
growth factors!
stimulates!
further cell division.
8.9 Growth factors signal the cell cycle control
system!
• The cell cycle control system regulates the
events of the cell cycle!
• If a growth factor is not released at three major
checkpoints, the cell cycle will stop!
– G1 of interphase !
– G2 of interphase!
– M phase
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 8-9a
G1 checkpoint
G0
Control!
system
G1
M
G2
PowerPoint Lectures for!
Biology: Concepts and Connections, Fifth Edition!
– Campbell, Reece, Taylor, and Simon
M checkpoint
Lectures by Chris Romero G2 checkpoint
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
S
• How a growth factor might affect the cell cycle
control system!
– Cell has receptor protein in plasma
membrane!
– Binding of growth factor to receptor triggers a
signal transduction pathway!
• Molecules induce changes in other molecules!
– Signal finally overrides brakes on the cell
cycle control system
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 8-9b
Growth factor
Plasma membrane
Relay!
proteins
Receptor!
protein
Signal!
transduction!
pathway
G1 checkpoint
G1
PowerPoint Lectures for!
Biology: Concepts and Connections, Fifth Edition!
– Campbell, Reece, Taylor, and Simon
Lectures by Chris Romero
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Control!
system
M
S
G2
CONNECTION
8.10 Growing out of control, cancer cells produce
malignant tumors!
• Cancer cells do not respond normally to the cell
cycle control system!
– Divide excessively!
– Can invade other tissues!
– May kill the organism
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• If an abnormal cell avoids destruction by the
immune system, it may form a tumor!
– Benign: abnormal cells remain at original site!
– Malignant: abnormal cells can spread to other
tissues and parts of the body!
– Metastasis: spread of cancer cells through the
circulatory system
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 8-10
Lymph!
vessels!
Tumor
Blood
vessel!
Glandular!
tissue!
A tumor grows from a!
PowerPoint
single cancerLectures
cell. !
Cancer cells invade!
Neighboring tissue. !
for!
Biology: Concepts and Connections, Fifth Edition!
– Campbell, Reece, Taylor, and Simon
Lectures by Chris Romero
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Cancer cells spread through!
lymph and blood vessels to!
other parts of the body. !
• Cancers are named according to location of
origin!
– Carcinoma: external or internal body
coverings!
– Sarcoma: tissues that support the body!
– Leukemia and lymphoma: blood-forming
tissues!
• Radiation and chemotherapy are effective as
cancer treatments because they interfere with
cell division
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
8.11 Review of the functions of mitosis: growth,
cell replacement, and asexual reproduction!
• When the cell cycle operates normally, mitotic
cell division functions in!
– Growth!
– Replacement of damaged or lost cells!
– Asexual reproduction
Video: Hydra Budding
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings