Cell Structure & Function

Cell Structure & Function

http://koning.ecsu.ctstateu.edu/cell/cell.html

Definition of CellDefinition of Cell

A cell is the smallest unit that is capable of

performing life functions.

A cell is the smallest unit that is capable of

performing life functions.

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Cell Theory

Cell Theory

1. All organisms are composed of cells.

2. Cells are basic unit of structure and function in living things

3. Cells arise only from pre-existing (OLD) cells.

Two Types of Cells

Two Types of Cells

•Prokaryotic•Eukaryotic•Prokaryotic•Eukaryotic

Prokaryote cells are smaller and simpler

Commonly known as bacteria

10-100 microns in size

Single-celled(unicellular) or

Filamentous (strings of single cells)

These are prokaryote E. coli bacteria on the head of a steel pin.

Prokaryotesa. Are generally smaller than eukaryotic cells

b. Have no nucleus

c. Carry out all of life’s processes

d. Ex: bacteria

Eukaryotesa. Are generally larger and more complex than

prokaryotes

b. Contain dozens of membrane bound structures that are specialized

c. Nucleus separates DNA from rest of cell

There are 3 major types of microscopes

1) Light Microscope• Magnifies 40 – 1,000 times depending

on objective being used• Used to magnify objects that light can

pass through.• Uses slides

Exploring the Cell

2) Scanning Electron Microscope

Uses electrons to illuminate objects (3D view)

Can magnify from 30,000 to 9 million times

Mostly large institutions have them

Costly to own and maintain

Can only be used to look at dead specimens

Transmission Electron Microscope

•TEM- thin slices need to be made to have clear images, images are 2-D

•Useful for studying internal structures

Organelles are membrane-bound cell parts

Mini “organs” that have unique structures and functions

Located in cytoplasm

Cell membrane

delicate lipid and protein skin around cytoplasm

found in all cells

Cell Structures

Nucleus

a membrane-bound sac evolved to store the cell’s chromosomes(DNA)

has pores: holes

Nucleolus

inside nucleus

location of ribosome factory

made or RNA

mitochondrion

makes the cell’s energy

the more energy the cell needs, the more mitochondria it has

Ribosomes

build proteins from amino acids in cytoplasm

may be free-floating, or

may be attached to ER

made of RNA

Endoplasmic reticulum

may be smooth: builds lipids and carbohydrates

may be rough: stores proteins made by attached ribosomes

Golgi Complex

takes in sacs of raw material from ER

sends out sacs containing finished cell products

Lysosomes

sacs filled with digestive enzymes

digest worn out cell parts

digest food absorbed by cell

Centrioles

pair of bundled tubes

organize cell division

Cytoskeletonmade of microtubules

found throughout cytoplasm

gives shape to cell & moves organelles around inside.

“Typical” Animal Cell

http://web.jjay.cuny.edu/~acarpi/NSC/images/cell.gif

Structures found in plant cells

Cell wall

very strong

made of cellulose

protects cell from bursting

glued to other cells next door

Vacuole

huge water-filled sac

keeps cell pressurized

stores starch

Chloroplasts

filled with chlorophyll

turn solar energy into food energy

How are plant and animal cells different?

Structure Animal cells Plant cells

cell membrane Yes yes

nucleus Yes yes

nucleolus yes yes

ribosomes yes yes

ER yes yes

Golgi yes yes

centrioles yes no

cell wall no yes

mitochondria yes yes

cholorplasts no yes

One big vacuole no yes

cytoskeleton yes Yes