Cell Growth and Reproduction

1
Chapter 9
Cell Growth and Reproduction
2
Chapter Objective

• Describe the processes of cell growth and cell
  reproduction (SPI 3210.1.6.)

3
Section 9.1The cell cycle multiplies cells
4
Section Objectives

1. Describe the structure and function of a
   chromosome.
2. Given a diagram or picture of a cell, identify
   whether the cell is in the interphase or mitotic
   phase of the cell cycle and explain what happens
   during each phase.

5
Key Terms

• chromatin
• chromosome
• sister chromatid
• centromere
• cell cycle

• interphase
• mitotic phase
• mitosis
• cytokinesis

6
Large Cells Can Have Problems!

• As cells grow, their volume increases much more
  rapidly than their surface area!

7
Why is size a problem?
Large cells may have difficulty supplying
nutrients and expelling enough waste products.
8
Transport of Substances

• Substances move by diffusion or by motor
  proteins.
• Diffusion over large distances is slow and
  inefficient.
• Small cells maintain more efficient transport
  systems.

9
Cellular Communications

• The need for signaling proteins to move
  throughout the cell also limits cell size.
• Cell size affects the ability of the cell to
  communicate instructions for cellular functions.

10
Cells Divide at Different Rates

• How often a cell divides depends on the type of
  cell (its function).
• Eukaryotic cells that do divide undergo an
  orderly sequence of events known as the cell
  cycle.

11
The Cell Cycle

• Cell division prevents the cell from becoming too
  large.
• It also is the way the cell reproduces so that
  you grow and heal certain injuries.
• Cells reproduce by a cycle of growing and
  dividing called the cell cycle.

12
The Cell Cycle

• Interphase - the cell grows, carries out cellular
  functions, and replicates.
• Mitosis - the cells nucleus and nuclear material
  divide.
• Cytokinesis - a cells cytoplasm divides.

13
Phases of The Cell Cycle

• Interphase
• G1 (Gap1)
• S (DNA Synthesis)
• G2 (Gap2)
• Mitotic (M) Phase
• Cytokinesis

14
The Cell Cycle
15
The Stages of Interphase

• 1st stage - G1
• The cell is growing, carrying out normal cell
  functions, and preparing to replicate DNA.

16
The Stages of Interphase

• 2nd Stage S
• The cell copies its DNA in preparation for cell
  division.

17
S phase Genetic material (chromosomes) duplicate)
18
The Stages of Interphase

• 3rd Stage - G2
• Cell prepares for division of nucleus (mitosis).

19
Mitosis and Cytokinesis

• Concept 9.2

Cells divide during the mitotic phase
20
Section Objectives

• Given diagrams or pictures of cells in various
  stages of the mitotic phase of the cell cycle,
  identify and name the stages and explain what
  happens during each stage.

21
Key Terms

• prophase
• sister chromatid
• centromere
• spindle apparatus

• metaphase
• anaphase
• telophase

22
Mitotic Phase

• Unique to eukaryotes
• Very accurate (error rate 1/100,000 cell
  divisions)

23
Mitosis Duplicates the Nucleus (Chromosomes)
24
The Mitotic Phase
25
Stages of Mitosis
Prison (Prophase) Men (Metaphase) Are
(Anaphase) Thin (Telophase)
26
(No Transcript)
27
Prophase

• The cells chromatin tightens.
• Sister chromatids are attached at the centromere.
• Spindle fibers form in the cytoplasm.

28

• The nuclear envelope seems to disappear.

• Spindle fibers attach to the sister chromatids.

29
Metaphase

• Sister chromatids line up in the middle of the
  cell.

30
Anaphase

• Microtubules of the spindle apparatus begin to
  shorten.
• Sister chromatids separate.
• Chromosomes move toward the poles of the cell.

31
Telophase

• The chromosomes arrive at the poles and begin to
  relax.
• Two new nuclear membranes begin to form and the
  nucleoli reappear.
• The spindle apparatus disassembles.

32
(No Transcript)
33
(No Transcript)
34
Cytokinesis
Process by which the cytoplasm of a cell is
divided in two usually follows mitosis and
meiosis.
35
Cytokinesis in Animal Cells
Microfilaments constrict, or pinch, the cytoplasm
to create a cleavage furrow
36
Cytokinesis in Plant Cells
Cell wall too rigid for microfilaments to
constrict cell. Cell plate created.
37
How Cytokinesis Differs in Plants
38

• Section 9.3
• Cell Cycle Regulation

39
Terms to know

• cyclin
• cyclin-dependent kinase
• cancer
• carcinogen
• apoptosis
• stem cell
• benign tumor
• malignant tumor
• metastasis

40
Normal Cell Cycle

• Different cyclin/CDK combinations signal other
  activities, including DNA replication, protein
  synthesis, and nuclear division throughout the
  cell cycle.

41
Quality Control Checkpoints

• Checkpoints in the cell cycle can stop the cycle
  if something goes wrong.

42
Apoptosis

• Programmed cell death
• Cells going through apoptosis actually shrink and
  shrivel in a controlled process.
• Signals from the checkpoints can start apoptosis.

43
(No Transcript)
44
A disease caused by severe disruption of the
mechanisms that normally control the cell cycle.
Cancer
45
Abnormal Cell Cycle Cancer

• Cancer is the uncontrolled growth and division of
  cells.
• Cancer cells can kill an organism by crowding out
  normal cells, resulting in the loss of tissue
  function.

46
Cancerous cells reproduce at an abnormally fast
rate!
47
Benign An abnormal mass of normal cells.
Types of Tumors
Malignant A mass of abnormal cells resulting
from uncontrolled cell division.
48
The spread of cancer cells beyond their original
site
Metastasis
49
Causes of cancer

• Genetic mutations
• Food
• Hormones
• Radiation
• Tobacco
• Weight physical activity
• Workplace environment

50
Cancer Treatments

• Surgery
• Radiation therapy
• Chemotherapy
• A mix of the three

51
Stem Cells

• Unspecialized cells that can develop into
  specialized cells when under the right conditions

52
Embryonic Stem Cells

• After fertilization, the resulting mass of cells
  divides repeatedly until there are about
  100150 cells. These cells have not become
  specialized.

53
Adult Stem Cells

• Found in various tissues in the body and might be
  used to maintain and repair the same kind of
  tissue
• Less controversial because the adult stem cells
  can be obtained with the consent of their donor

54
Vocabulary Review
chromatin combination of DNA and protein
molecules, in the form of long, thin fibers,
making up the genetic material in the nucleus of
a eukaryotic cell.
chromosome condensed threads of genetic material
formed from chromatin as a cell prepares to
divide.
sister chromatid one of a pair of identical
chromosomes created during the S phase before a
cell actually divides.
55
Vocabulary Review (contd)
centromere region where two sister chromatids
are joined tightly together.
cell cycle sequence of events from the
production of a eukaryotic cell to the time the
cell itself reproduces.
interphase stage of the cell cycle during which
a cell carries out its metabolic processes and
performs its functions in the body.
56
Vocabulary Review (contd)
mitotic phase stage of the cell cycle when a
cell is actively dividing.
mitosis process by which the nucleus and
duplicated chromosomes of a cell divide and are
evenly distributed, forming two daughter nuclei.
cytokinesis process by which the cytoplasm of a
cell is divided in two usually follows mitosis
and meiosis.