Download THE CELL

SBI 3C
SEPTEMBER 2012
THE BIG QUESTION
HOW DO YOU KNOW IF
SOMETHING IS ALIVE??
CHARACTERISTICS OF LIVING THINGS:
Stimulus and response
 Require energy
 Produce waste
 Grow and reproduce

THE CELL THEORY
All living things are made up of cells
2. The cell is the basic functional unit of
living things
3. All cells come from pre-existing cells
through cell division
1.
WHAT DO CELLS DO?

Cellular respiration:
 In the mitochondria
 glucose + oxygen  energy + water + carbon dioxide

Absorption:
 Bring in water and nutrients into cells

Excretion:
 Remove waste products from cells

Biosynthesis:
 Make larger molecules out of smaller ones
 Examples:
○ Amino acids join together to make protein
○ Sugar molecules join together to make carbohydrates
GENERAL STRUCTURE OF A CELL:
Inside is a liquid, water-based solution
called cytoplasm
 Little organs (organelles) sit in the liquid
 Cells are surrounded by a membrane
that separates them from the outside

organelle
membrane
cytoplasm
TYPES OF CELLS:

There are 2 types of cells:
 Animal Cells
 Plant Cells
ANIMAL CELLS:
PLANT CELLS:
ORGANELLES:

CELL WALL:
 Only in plants
 Firm but porous, surrounds cells giving them
rigidity

CELL MEMBRANE:
 Only in animal cells
 Surrounds cell and organelles in cell
 Composed of a bilayer (double layer) of fat (lipid)
molecules called phospholipid bilayer
NUCLEUS:
 Control centre of the cell
 Contains DNA
 Surrounded by a porous
double membrane
(nuclear envelope)
 Filled with nucleoplasm
(like cytoplasm)
DNA AND RNA:
 DNA: double stranded,
found in nucleus
 RNA: single stranded,
found in cytoplasm
 Chemical storage of
information needed to
keep the cell alive and
functioning properly
RNA
DNA
RIBOSOMES:
 Used to produce protein
 Either free floating in cytoplasm or attached
to membranes
 Very small
ENDOPLASMIC RETICULUM:
 System of tubes and canals that attach to the nuclear
envelope
 Two types:
○ Rough ER (RER) has ribosomes and is the site of protein
manufacturing
○ Smooth ER (SER) no ribosomes and is where fat
molecules are produced
GOLGI APPARATUS:
Stacks of membraneous tubes
 Takes proteins from the ER and
changes them
 Packages them into vesicles to be
released outside the cells

LYSOSOMES:
 Found only in animal cells
 Contain protein that help to digest food or kill
invading bacteria or viruses
 Also kills dead or dying cells, called the
suicide sac
MITOCHONDRIA:
Shaped like a kidney bean
 Float in the cytoplasm
 Site of chemical reactions that produce
energy for the cell
 Powerhouse of the cell

PLASTIDS:



Only in plant cells
Fairly large
Different types have different functions:
 storage (amyloplast - stores starch)
 energy production(chloroplast-site of photosynthesis)
VACUOLES:
Common in plant cells
 Large, membrane bound sac
 Filled with watery solution containing
dissolved sugars, proteins, minerals
 Pressure from water (turgor pressure)
prevents plants from wilting
