CELL CYCLE, DNA REPLICATION AND MITOSIS

Amoeba Sister: Cell Cycle

https://www.youtube.com/watch?v=gwcwSZIfKlM

The Cell CycleP M A T Cyto-

kinesis

G1 – 1st period of growth 1. Increase in size2. Makes new proteins and

organelles.

CELL CYCLE, DNA REPLICATION AND MITOSIS

Reasons why cells divide:

1. Repair

2. Replace old or damage cells

3. Reproduction

Cellular GrowthCopyright © McGraw-Hill Education

Cell Size Limitations

Ratio of surface area to volume

• Smaller cells can transport substances more easily

• Diffusion is inefficient over longer distances

• Cytoskeleton less efficient when cells are larger

• Cellular communication more efficient in smaller cells

Works

Better

Cellular GrowthCopyright © McGraw-Hill Education

The Cell Cycle

• Three main stages of the cell cycle:

• Interphase: stage during which the cells grows, carries out cellular

functions, and replicates its DNA.

• Mitosis: the cell’s nucleus and nuclear material divide; has four

substages.

• Cytokinesis: cell’s cytoplasm divides, creating two new cells.

CELL CYCLEIS THE SERIES OF EVENTS THAT TAKE PLACE IN A CELL LEADING TO ITS DIVISION AND DUPLICATION (REPLICATION) THAT PRODUCES TWO DAUGHTER CELLS.

G0

The Cell Cycle

Eukaryotic cells divide via the

cell cycle.

Prokaryotic cells divide via

binary fission.

Many different Diagrams

CELL CYCLE

The sequence of growth and division of a cell

An average cycle may be 22 hours

Two general periods:

1. growth phase (interphase)

2. division phase (mitosis)

INTERPHASE (GROWTH PHASE)

Most of the cell’s life is spent in interphase

Longest phase –(90% of cell’s growth)

Centrioles – help to organize cell division

Chromatin – DNA bound protein within the nucleus

The Cell CycleP M A T Cyto-

kinesis

G1 – 1st period of growth 1. Increase in size2. Makes new proteins and

organelles.

INTERPHASE (GROWTH PHASE)

G1 – 1st period of growth

1. Increase in size.

2. Makes new proteins and

organelles.

G0 – Resting Phase

1. If cells don’t go into this phase it could

cause cancer (tumor)

S – DNA is synthesized or replicated

1. Chromosomes are replicated.

2. New DNA molecules are made.

G2 – final cell growth

1. Shortest phase

2. Prepares cell for mitosis

Not a part of Interphase

Mitosis –Cell Division

Cytokinesis- Division on the cytoplasm (2 new cells)

New DNA is formed during 4 phases:

The Cell CycleP M A T Cyto-

kinesis

G1 – 1st period of growth 1. Increase in size2. Makes new proteins and

organelles.

CELL CYCLE

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WHERE HAVE SCIENTISTS BEEN?A BRIEF HISTORY

Oswald Avery (1944) Discovered that the

nucleic acid DNA stores and transmits the genetic information from one generation of an organism to the next

ERWIN CHARGAFF (1950)

Discovered a relationship in the nitrogenous bases

Adenine (A) = Thymine (T)

Guanine (G) = Cytosine (C)

ALFRED HERSHEY & MARTHA CHASE (1952)

Concluded that the genetic material of the bacteriophage was DNA, not protein.

Used radioactive phosphorous and sulfur.

ROSALIND FRANKLIN (1952)

Took an x-ray of the DNA structure so the patterns could be seen.

The x-rays show that DNA is twisted around each other like a helix and has two strands.

(1953)Watson and Crick proposed that DNA is made up of 2 chains of nucleotides held together

by nitrogenous bases & that the 2 strands are twisted together in a shape called a double helix.

DNA REPLICATION: AMOEBA SISTERS

https://www.youtube.com/watch?v=5qSrmeiWsuc&index=26&list=PLvLzbk8R9i4go1-xj7jLqELF2WhbZ4XlM

1. What is the name of this monomer?

2. What is the name of the polymer or

macromolecule to which this monomer

belongs?

REVISIT PRI0R KNOWLEDGE

THE STRUCTURE OF DNA

DNA is a polymer made up of repeating monomers of nucleotides.

DNA determines an organism’s traits by controlling the manufacturing of proteins.

The sequencing of nucleotides forms unique genetic information.

OVERVIEW OF DNA

Order from smallest to largest

DNA Double Helix-Nucleosome-Coils-Supercoils-Chromosome

The nucleus of

a cell contains

chromosomes

Which

are

made

up of

coiled

DNA

Eukaryotic chromosomes contain DNA wrapped around proteins called Histones.

Chromosome

Solenoid

Histone Proteins

DNA Double Helix

Each strand of

DNA is made

up

of subunits

called

Each nucleotide is

constructed of 3

parts:

a PHOSPHATE group,

a SUGAR molecule

&

1 of 4 nitrogen bases

Adenine (A)

Guanine (G)

Cytosine (C)

Thymine (T)

Purines

Pyrimidines

DNA REPLICATION

Copying process by which a cell duplicates its DNA

DNA molecule separates into two strands, then produces two new complementary strands following the rules of base pairing

Each strand of the double helix of DNA serves as a template for the new strand

Enzyme (Helicase) unzips DNA by breaking the hydrogen bonds between the base pairs, which produces two replication forks

DNA polymerase

Joins individual nucleotides to make a new strand.

Proofreads each new strand.

Joins the hydrogen bonds

Ligase: Enzyme creating the covalent bond that connect the sugar phosphate backbone.

DNA REPLICATION

Because of the

hydrogen bonds,

Adenine can only

bond with Thymine

& Guanine can only

bond with Cytosine

*A purine is always paired with a

pyrimidine.

Thymine

Adenine

Cytosine

Guanine

This is known as

COMPLEMENTARY base pairing

For example: GCA ATC TA

CGT TAG AT

Now you try:

CCA GAT TGA

GGT CTA ACT

In class assignment for all classes

DNA REPLICATION FORK

KEY

PAP Homework

G2 PHASE

G2 – final cell growth1. Shortest phase2. Prepares cell for mitosis3. Check for no mistakes in the chromosomes4. Repairs any Mistakes

The Cell CycleP M A T Cyto-

kinesis

OCCURRENCES DURINGTHE CELL CYCLE

MITOSIS:

The Making of Body Cells (Somatic Cells)

TERMS TO KNOW

Chromosome – contains genetic information (DNA) passed from one generation to the next

Spindle – microtubule that helps separate chromosomes

A – Centromere:

center of chromosome

B – Chromatids: two

identical “sister” parts

of the chromosome

MITOSIS(DIVISION PHASE OF BODY CELLS)

4 Phases:

(PMAT)

1)Prophase

2)Metaphase

3)Anaphase

4)Telophase

Mitosis Mnemonic &Hand Motions

MITOSIS ACRONYM

Mitosis only

Passed (prophase)

My (metaphase)

Algebra (anaphase)

Test (telophase)

All cell cycle

I (interphase)

Passed (prophase)

My (metaphase)

Algebra (anaphase)

Test (telophase)

Corrections (cytokinesis)

Interphase Prophase Metaphase

Anaphase Telophase Cytokinesis

Interphase

Prophase

Metaphase

Anaphase

Telophase

Cytokinesis

CYTOKINESIS

Animal cells

The cell membrane is drawn inward forming a cleavagefurrow until the cytoplasm is pinched into 2 nearly equal parts

Plant cells

A cell plate gradually develops into a separating membrane.

CELL CYCLE: WHAT STAGE OF INTERPHASE IS A?WHAT STAGE IS B?

All classes

CELL CYCLE AND CANCER

https://www.youtube.com/watch?v=IeUANxFVXKc&list=PL3Tg4mErzFVdvHixfoagIBFUWHGNoIgZ4

CANCER

Cancer is a disorder where the cell has uncontrolled growth. (Does not go into the G0 phase

Cancer cells do NOT respond to regulators that control timing of cell cycle (cyclins).

This causes the cells to form masses called tumors, which can damage surrounding tissues.

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

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

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

Aka: Mutagenic Agents

CANCER CELLS

METASTASIZING CANCER CELL

LUNG CANCER CELLS