CHAPTER 4 A TOUR OF THE CELL

4.2 Most cells are microscopicObjectives: 1) Be able to explain why cell size is limited.

III. Surface area-to-volume ratioA. Surface Area(SA)

1. The measurement of the exterior of the cell2. To calculate take the # of sides and multiply by the length and width of sides

B. Volume1. The measurement of the internal contents of the cell2. To calculate multiply the length x width x height

I. DiffusionA. One of many ways cells transport materials throughout the cellB. Cell parts must not be too far from the cell membrane

1. Diffusion is very fast and efficient over short distances2. Diffusion becomes slow and inefficient as distances become larger

II. DNA limits cell sizeA. DNA contains the directions for all cell activity

1. For exampleProteinsa. If cell is too large the DNA cannot make proteins fast enough to

support the cells needs

L=1

W=1

H=1

SA= 6X1X1=6

Volume= 1X1X1=1

C. As a cell grows so to does its SA and volume1. The problem the volume increases faster than the

SA

W=2

H=2

L=2

SA=24Volume=8

4X the SA8X the volume

2. How does the SA-to-volume ratio affect the function of the cella. If cell size doubles, the cell would require

8x more nutrients & would have 8x more waste to excrete

1. SA would only increase by 4x2. The plasma membrane could not accommodate this increase

4.3 Prokaryotic cells are structurally simpler than eukaryotic cellsObjective: 1) Be able to briefly explain the difference between a prokaryotic cell and a eukaryotic cell.I. Prokaryotic vs. Eukaryotic

Prokaryotes Eukaryotes

No Nucleus (have a Nucleoid) Nucleus

No membrane bound organelles Membrane bound organelles

Cell membrane Cell membrane

Cytoplasm Cytoplasm

Ribosomes Ribosomes

I. Organelle IntroA. A specialized compartment that carries out 1 or

more specific functionsB. 4 basic functional groups

1. Manufacturinga. Nucleus, ribosomes, endoplasmic reticulum,

golgi apparatus

4.4 Eukaryotic cells are partitioned into functional componentsObjective: 1) Be able to explain the importance of organelles

C. How do organelles benefit a eukaryotic cell1. Allows specialized activities that require

different environments to be carried out simultaneously

2. Hydrolysis of moleculesa. Lysosomes & vacuoles

3. Energy processinga. Mitochondria & chloroplast

4. Structural support, movement, communicationa. Cytoskeleton, plasma membrane, cell wall

4.6-4.13 Cell structures involved in manufacturing and breakdownObjectives: 1) Be able to describe structure and functions of organelles

I. 4.6-The nucleus is the cells genetic control center

A. The brains1. Directs all cell activity

a. Tells all other organelles what to do by directing protein synthesis

2. Storage center for cells DNA3. Nuclear envelope

a. Bilayer membrane that surrounds the cell controlling what comes in and out

II. 4.7- Ribosomes make proteins for use in the cell and exportA. Site were proteins are assembled

B. 2 types of ribosomes1. Free ribosomes

a. Suspended in the cytoplasmb. Manufacture proteins that function within the cytoplasm

2. Bound ribosomes1. Attached to the endoplasmic reticulum or nuclear envelope2. Manufacture proteins that will be inserted into the plasma

membrane, exported from the cell

III. 4.9-The endoplasmic reticulum is a biosynthetic reticulum

A. Smooth endoplasmic reticulum1. No ribosomes attached to2. Synthesizes lipids (mainly oils)3. Calcium ion storage B. Rough endoplasmic reticulum1. Ribosomes attached to2. Synthesize phospholipids & proteins

IV. 4.10-Golgi apparatus finishes, sorts, & ships cell products

A. The packaging and distribution center of the cellB. Receives & modifies products from endoplasmic

reticulum1. As products travel through the golgi apparatus

they will be modified before being shipped out to the cell or other cells

V. 4.11-Lysosomes are digestive compartments within a cellA. The digestive system and recycler of the cell

1. Cleans up waste and damaged cell structures & recycles their organic components

2. Breaks down nutrient material for the cell to utilize

B. Structure: Demonstrating the importance of compartmentalization1. Membrane enclosed compartment containing digestive enzymes

a. Enzymes are potent enough to digest the entire cellb. Membrane contains enzymes so as to not harm the rest of the cell

1. Except under certain curcumstances

C. Function1. Digest food providing nutrients to the cell2. Digest worn out or damaged organelles recycling their organic

compounds3. Digest harmful pathogens like bacteria and viruses & recycle

I. 4.14-Mitochondria harvest chemical energy from food The power plantA. Creates the energy needed by the cell by cellular respiration

1. Converts food (sugar) into ATP

4.14-4.15 Energy-converting organellesObjective: 1) Be able to describe structure and functions of organelles

B. Structure1. Outer membrane/Intermembrane space/Inner membrane/Matrix

a. Matrix1. Contains the mitochondrial DNA and necessary ribosomes

II. 4.15-Chloroplasts convert solar energy to chemical energy

A. Provides the necessary sugar that is needed by the mitochondria

B. Structured very similar as mitochondria1. Outer membrane/intermembrane space/inner

membrane/ stromaa. Stroma1. Contains the chloroplast DNA and necessary

ribosomes

READ 4.16 ON YOUR OWN

4.17 Internal supportI. Cytoskeleton

A. A network of protein fibers that provides the support allowing the cell to maintain its shape and provide locomotion.

IV. Plant cells vs. Animal cells

Plants Animals

Plasma membrane Plasma membrane

Nucleus Nucleus

Golgi Apparatus Golgi apparatus

Mitochondria Mitochondria

Chloroplast NO chloroplast

Cell Wall NO cell wall