Chapter 3

Cell Structure and Function

Animal Cell

• 1. cell (plasma) membrane –

thin, transparent, 2-layered, semi-permeable

(porous), flexible

-controls what enters and leaves cell

-separates cell from its environment

2. nucleus –

command center of the cell; most cells have only one; some have >1

DNA:

a) chromatin – mass of fibers scattered

through the nucleus (thread-like)

b) chromosomes – compact chromatin

-direct & store instructions for all cell

functions

-control inheritance of traits

c) nuclear membrane –

2-layered, semi-permeable, porous,

surrounds nucleus

d) nucleolus – cell may have 1 or 2; produce

granules rich in RNA, each granule will

become part of a ribosome

e) nucleoplasm - fluid within the nucleus

* 3. cytoplasm – jelly-like fluid outside nucleus, but within cell -transports chemical substances within the cell

4. endoplasmic reticulum – network of interconnected membranes (ER)

-storage, separation, and transport of substances made within the cell (mostly proteins) a) rough ER – dotted with ribosomes b) smooth ER – no ribosomes

5. Golgi apparatus (body) – stack of flattened

membranes where proteins are packaged

and distributed

6. vacuole – clear, fluid-filled sac; used for

storage

7. lysosome – small sac filled with powerful

chemicals which break down food

molecules and digest old organelles;

surrounded by a membrane

8. mitochondria – “powerhouse” of the cell;

bean-shaped; one of the largest and most

numerous; site of cellular respiration

Cytoskeleton

9. microtubules – long, thin, hollow cylinders;

in cytoplasm, they support cell (shape) or

are arranged in bundles in other structures

(like cilia, flagella, or centrioles* - only in

animal cells)

10. microfilaments – tiny-threadlike fibers made

of protein; contract like muscle cells for

movement

11. ribosomes – tiny, round bodies involved

in protein synthesis from amino acids

Plant Cell

-have a cell wall composed of cellulose (provides structure and support)-contain chloroplasts – function in

photosynthesis (football shaped), starch granules – spherical, function in food storage, and carotens – contain orange pigments;

spherical-plant cells are rectangular in shape (animal

cells are spherical)-have a large water vacuole which provides

turgor pressure