Chapter 6
A Tour of the Cell
Cell Review

Cell – The smallest basic unit of structure and function that show the
characteristics of life

Unicellular – made up of a single cell


Ex Bacteria
Multicellular – made up of multiple cells
Levels
of organization
Cell--tissue--organ--organ
organism
system--
Cell History

Robert Hooke – (mid 1600s) – examined cork and was the first to see “cells”

Anton von Leeuwenhoek – made single-lens microscope and was the first to see
living cells
Cell Theory
 Schleiden
All
plants are made up of cells
 Schwann
All
– studied plants
– studied animals
animals are made of cells
 Virchow
All
cells come from preexisting cells
 1.
All living organisms are made up of cells
 2.
All cells carry on life activities
 3.
New cells arise only from other living cells
Two Basic Cell Types

Prokaryotic – lack any internal membrane-bound structures and nuclei
Single-celled

organisms: bacteria
Eukaryotic – have nuclei and membrane-bound structures
Multicellular
organisms – plants, animals,
fungi, protists
Prokaryotic vs Eukaryotic
Cell Size

Cells are all different shapes and sizes

Vary from 2m to .2 micrometers
Ex:
nerve cells –
1 to 2 meters long
Ex:
Chicken Egg – single cell
Cell Parts

Cell membrane – outer covering separates the cell
from its surrounding environment

Made up of a phospholipid bilayer, selectively
permeable

3 functions
1.
Protect inside of cell separating it from
outside
2.
Support cell and give it shape
3.
Control the passage of substances
Cell Parts

Membrane Proteins
Integral
proteins (those
embedded within)
Transport molecules
Peripheral proteins (lie on one
side)
Aid in chemical rxns

Cytoplasm – aqueous fluid inside the cell that contains
organelles
Organelles

Organelles – membrane-bound structures having one or
more specialized functions
Maintain
the life of the cell

Ribosomes – where proteins are made

Endoplasmic Reticulum (ER) – intracellular pathway used in
transport

Rough ER – ribosomes attached here, site in which proteins
are made and transported

Smooth ER – Where lipids are made
Ex:
produce steroids in gland cells
Organelles

Golgi Apparatus – processes, packages, and secretes modified proteins for
export from cell

Lysosomes – small sacs that contain digestive enzymes
Ex:

Webbed hands
Centriole – 2 rod-shaped organelles located near the nucleus of an animal cell
involved in cell reproduction
Organelles
 Nucleus
– Control center of the cell
 Nuclear Membrane – separates the nucleus
from the rest of the cell
 Nucleolus – place in which ribosomes are
made
 Chromosomes – structures found inside
nucleus that control heredity
 Mitochondria
– site of cellular respiration,
powerhouse of cells
 Where
we get our energy ATP
Plant Cell Parts

Cell Wall – rigid outer covering just outside
a plant cell that gives shape and structure

Vacuole – storage site of cell

Chloroplasts – structures that contain the
pigment chlorophyll that give plants their
green color
Animal Cell Diagram
Plant Cell Diagram
The Cytoskeleton

Cytoskeleton – long protein strands within the cytoplasm that gives the cell
structure

Microfilaments – small protein threads
 Actin
– protein found in the microfilaments
that help muscle contraction

Microtubules – long, hollow tubes made up of the protein tubulin

Cilia – small hair-like projections used in cell movement

Flagella – long whip-like tail used for movement
Cell Processes

Homeostasis – ability to maintain a stable internal environment

Passive Transport – the movement of substances across a cell membrane without
the use of energy by the cell

Diffusion – movement of molecules from an area of higher to lower
concentration
Ex.

Perfume
Facilitated diffusion – type of passive transport in which carriers transport
molecules without using energy
Ex:
Glucose
Osmosis

Osmosis – process by which water molecules diffuse across a cell membrane
from higher to lower concentration
Hypertonic
– solute concentration outside
cell is greater than inside cell
Hypotonic – solute concentration outside
cell is lower than inside the cell
Isotonic – solute concentration is the same
inside and out
 Turgor
pressure – pressure that water
exerts against a cell wall
Cytolysis – swelling of cells due to an intake
of water in a hypotonic environment
Ex: animal cells (red blood cells)
Plasmolysis - shrinking of cytoplasm due to loss
of water in a hypertonic environment
Ex: Leaves wilting
Active Transport

Active Transport – movement of
molecules across the
concentration gradient from
lesser to greater with the use
of energy (supplied by ATP)
Ex.
Sodium
Potassium
Pump
Movement in Vesicles
(large molecules)

Endocytosis – process by which cells ingest external fluid, macromolecules, and
large particles by vesicle
Phagocytosis
– transport of large particles
or whole cells
Movement in Vesicles
(large molecules)

Exocytosis – process by which a substance is released from the cell through a
vesicle that transports the substance out of the cell