Chap 3 - Cells

Learning Objectives:

1. Describe the structure and function of the major cell organelles.

2. List the phases of the cell cycle and describe the key events in each phase.

3. Describe DNA replication.

Homework: Read Chapter 3, pgs 78 – 91 (Beginning with “The Cytoplasm” through “Chromatin”). Review Table 3.3, “Parts of the Cell: Structure and Function” pgs 88 – 89.

OPENING ACTIVITYCSI: Solving Crimes with DNA Evidence

Goal: To learn more about how DNA is used in crime-scene investigation

Instructions: ∙ Work in a group of 5-6 people. ∙ Quickly review the CSI case (there are 3 identical copies enclosed – share amongst yourselves). ∙ Use the CSI resource cards in the packet to help you formulate answers to the 5 questions on the first page (left-hand side) of the case. Try to formulate answers in your own words (re-state) rather than copying word-for- word. ∙ Be prepared to share and discuss your conclusions with the class.

http://www.cbs.com/primetime/csi_miami/

Follow-Up Discussion1. What is DNA?

2. What kinds of cells is DNA typically isolated from?

3. How is DNA tested for a possible match? Site at least 2 different types of tests and explain what they reveal.

4. What does “epithelials” refer to?

5. When a cell no longer has a nucleus, how can DNA be extracted form that cell?

PREDICTHow many cells in your body?

How many different kinds?

Typical Cell Structure, page 60Instructions: Individually, practice labeling the organelles on the handout.

The Plasma Membrane

• Surrounds the entire cell• Made of phospholipids and

___________• Is __________ permeable (it

allows some substances to pass through but not others)

• Substances move through the membrane _________ (not requiring any energy as in diffusion and filtration) or __________ (requiring energy form ATP)

Plasma membrane

Question: What is ATP? (*homework from Ch 2)

The Cytoplasm• The _______ _______ between the plasma

membrane and the nucleus

• Gelatin-like

• Consists of organelles – helps everything hang together

Nucleus• ______ _______ of the cell• Larger than most other cell organelles• Most cells have one nucleus but some are

multinucleated• 3 recognizable regions: 1. nuclear _________ (a double semi-

permeable membrane surrounding the nucleus) 2. _________ (dark spherical area on the

nucleus where ribosome subunits are assembled) 3. _________ (DNA containing area; when a cell

is preparing to divide, the chromatin coils and condenses to form short chromosomes.)

Mitochondria• ______ _______ of the cell

providing ATP• Contain both ____ and ____• Sausage-shaped membranous

organelles• In living cells they squirm,

elongate, and change shape• Consists of 2 membranes (an

outer and an inner membrane called the _______ which folds back and forth upon itself)

Ribosomes

• Small, dark-stained granules of ______ and a type of RNA called ________ RNA

• Sites of _______ synthesis

Endoplasmic Reticulum (ER)• A network within the cytoplasm (interconnected

tubes and membranes enclosing fluid-filled cavities or cisternae)

• Continuous with the nuclear membrane• There are 2 types: 1. ___________ (no part in protein synthesis –

they help with lipid metabolism, steriod-making hormones, detox of drugs, breakdown of stored glycogen)

2. ________ (studded with ribosomes which produce all proteins secreted form cells)

Golgi Apparatus

• Principle ‘traffic director’ for cellular _______

• Main function is to modify, concentrate, and package the ______ and ______ made at the rough ER

Lysosomes

• Spherical organelles containing _________ enzymes

• Digest _______, viruses, and toxins• Degrade worn out or nonfunctional __________• Perform glycogen breakdown and release• Breakdown nonuseful tissues such as the webs

between the developing fingers/toes of a fetus• Break down ______ to release Ca+ into the

blood

Peroxisomes

• Contain powerful enzymes like _________ (molecular O2 to detox harmful alcohols and formaldehyde). Also, neutralize dangerous free radicals.

Cytoskeleton(NOTE: Visible only when the cell is getting ready

to _________)

• Centrioles – small, barrell-shaped organelles oriented at right angles to one another

Cellular Extensions

• Cilia – ________ motile extensions

• Flagella – ________ undulating motile extensions

Review

• Which organelle is the command center of the cell and contains chromatin?

Which organelle contains oxidases to detox harmful substance?

Review Continued

• Organelle that contains digestive juices?

Organelle that supplies ATP?

The Cell Cycle_______ – cell carries out all routine functions; resting from dividing

a. ______ (G_) – growth phase; several minutes to hours in length b. _________ (S) - DNA is replicated c. ________ (G_) – growth and final preparations for division

Mitotic phase – series of events that parcel out the replicated DNA of the original (mother cell) into two new cells (________ cells)

Cytokinesis – ________ __ of the cytoplasm during late mitosis

Centrioles appear

A Closer Look at DNA Replication (S phase)

Before a cell can divide, its DNA must be _________ so that identical copies of the cell’s genes can be passed on to each of its offspring

1. Helix _______

2. 2 complimentary strands are in place exposing the _________ _____

3. Each strand serves as a template

DNA ReplicationInstructions: Complete the two new strands

of DNA.Leading Strand Lagging Strand

A - 1. ?

C - 2. ?

T - 3. ?

G - 4. ?

- T5. ?

- G6. ?

7. ? - A

8. ? - C

A Closer Look at Mitosis

http://www.cellsalive.com/mitosis.htm

Interphase (Before Mitosis)

• Cell carrying out ________ activities

• In late Interphase, ________ condenses and two pairs of _______ appear

• The nuclear membrane also begins to disintegrate

Nucleoli disappear also

Early and Late Prophase

•Asters are seen

• Chromatin condenses into chromosomes

•Chromosomes connected at midpoint (kinetochore) by centromere

Centrioles separate from one another; spindle fibers form between them

Metaphase

• Chromosomes cluster at the

______ of the cell with

centromeres precisely at

center/ equator of spindle

An enzyme called separase triggers separation of the chromosomes

Anaphase• Chromosomes are _____ ____ (now

called _________ )

• Moving chromatids look V-shaped

Telophase and Cytokinesis

• __ new cells forming

• Nucleus begins to _____ with new nuclear envelope, nucleolus, etc.

• _________ (pinching-in of cytoplasm) completes the division of the cell into 2 _______ cells

Review of the Mitosis

1. ?2. ?

3. ?4. ?

Abnormal Cell Cycles

Can result in _______ formation (cells growing and dividing much faster than normal)

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