Download B1: Cell Structure

Post-test questions
1. What does the cell theory state?
– All living things are made up of cells
– The cell is also the functional unit of life
– All living cells come from pre-existing cells
2. What are cells?
– The cell is the basic unit of life; the smallest
structure capable of performing all the functions
necessary for life.
Cells are specialized in structure and
function according to its job…
e.g. nerve cell transmits electrical response
e.g. muscle cells are able to contract and shorten
e.g. red blood cells do not contain a nucleus and
therefore they cannot divide. Additionally,
their small size allows them to fit into tiny
vessels
Post-test questions
3. What is the main difference between
prokaryotic and eukaryotic cells?
– Prokaryotes lack a nucleus as well as
membrane enclosed structures (e.g.
bacteria);
– whereas eukaryotes have a nucleus and
possess membrane enclosed structures
1.
pro = before
2.
karyotic = nucleus
3.
These were the first cells.
4.
They were primitive, small, had no
defined nucleus (no nuclear
membrane), and no membrane bound
cell organelles.
5.
They had ribosomes
1.
eu = true
2.
karyotic = nucleus
3.
These are modern cells.
4.
They have a nucleus and membranebound organelles.
5.
They are much larger (up to 1000X
larger).
4. What is an organelle?
– Small structures within a cell that have a specific
structure and function
Structure
Composed of a bi-layer of phospholipids with proteins
embedded in it
Function
• holds cell together and gives shape
• regulates the movement of substances in and
out of the cell
Nuclear
membrane
Nuclear pore
Nucleolus
Chromatin
Nucleoplasm
Structure:
• Dark granule in center
of cell
• Surrounded by a
double membrane
called the nuclear
envelope/membrane
Functions:
– Controls cell
activities through
protein synthesis
– Contains genetic info
– Directs cell division
– Site of DNA
replication and
transcription
Structure
• small, dark spot in
nucleus
• Made up of RNA
• No membrane
Function
• makes rRNA, which
then make
ribosomes
Structure:
• a double
membrane made
of phospholipids
which has nuclear
pores
Function
– Separates nuclear
material from
cytoplasm
– Pores allow RNA
and proteins in &
out of nucleus
1. Densely coiled DNA
wrapped around histone
proteins.
2. Is condensed into
chromosomes before
cell replication.
This is the
cytoplasm of
the nucleus
Structure
• double membrane
of phospholipids
• inner membrane is
very folded
=CRISTAE
(increased surface
area)
• fluid in between =
MATRIX
• has its own DNA
Mitochondria are used to convert the
chemical energy in food to ATP
Function:
• “powerhouse” – makes energy (ATP) for the cell in a
process called CELLULAR RESPIRATION
C6H12O6 + 6O2  6CO2 + 6H2O + ATP
Cristae (inner folds) provides more surface area for
enzyme reactions to make ATP
Structure
• membrane channels running from the nuclear envelope
throughout cytoplasm. It is a transport system.
2 Types:
•Has attached ribosomes.
•Usually connected with the
nuclear membrane.
•Ribosomes make proteins and
then place them in the rER
•The rER packages proteins in a
vesicle and sends them to the
Golgi Body.
SMOOTH ER:
•Has no attached ribosomes.
•Makes lipids and steroids.
•Also detoxifies harmful material or waste
products
•You’ll find a lot of sER in liver cells and
glands that make hormones.
Structure
• small, dense granules
made of rRNA & protein
• No membrane
• 2 subunits (large & small)
Function
• site of protein synthesis
(translation)
• Usually attached to rER
so proteins can be easily
exported
• Can be free in cytoplasm
-proteins not exported
(aka Polyribosome)
Structure
• Free floating group of
ribosomes
Function
• makes large proteins
(faster) with a single mRNA
molecule
(or golgi apparatus or golgi complex)
Structure
• stacks of flattened sacs
• surrounded by vesicles
Function
• Collects, sorts, packages and
distributes materials
• modifies proteins and lipids from
ER
DNA
copies a
gene as
RNA
RNA moves
through pore
and attaches
to ribosome to
make protein
Protein put
into RER,
then sent to
Golgi in a
vesicle
Golgi modifies protein,
stores it until needed, and
sends it to plasma
membrane in a vesicle.
Protein
released at
the Plasma
Membrane via
exocytosis
Structure
• Small, membranous
(bilayer) bound sac
usually made by Golgi
body
Function
• Storage sac (temporary
storage) ex. H2O, food,
digestive enzymes,
hormones.
2 types:
Transport vesicle: moves
substances from ER to
Golgi
Secretory vesicle: moves
substances from Golgi to
cell membrane
Structure
Function
• large vesicle (but small in
animals) and typically one
large in plants
• Membranous sacs
• Long term storage of H2O
with dissolved sugars and
salts
Plant cell Vacuole
Structure
• Double membraned
vacuoles with hydrolytic
(digestive) enzymes
Function
• Hydrolysis!
• destroys harmful
substances
• can kill the cell if it breaks
open - “suicide sacs”
• many in white blood cells
•
•
•
Also, breaks down organelles that
are not working anymore
in tadpoles destroys their tails
in human embryos destroys
webbing between fingers
http://highered.mcgraw-hill.com/olc/dl/120067/bio01.swf
LYSOSOME ANIMATION
series of protein fibres in the cytoplasm
• Maintains cell shape
• Monorail to transport organelles around
the cell
• Assemble and disassemble as needed
Made up of:
1. Microfilaments
2. Microtubules
3. intermediate filaments
•
•
•
•
aka actin filaments
Long & thin protein fibres
Anchored to the plasma membrane
Organelles move around the cytoplasm on these
•
•
•
•
Gives structure and support to cell membrane
Actin interacts with motor molecules such as myosin.
In the presence of ATP, myosin pulls actin along
Example: muscle cells
Structure
• Largest fibre
• Cylinder shaped & made of
tubulin (protein)
Function
• Anchor for organelles and
monorail for organelle
movement
• Used to make cilia,
flagellum & centrioles
Structure
• Intermediate size between
actin filaments and
microtubules
• made of keratin
Function
• Keeps the nucleus in place
• Cell-cell junctions, such as
those holding skin cells
tightly together
Structure
Function
• ‘Watery gel’ between
• Support & suspend
cell membrane and
organelles
nuclear envelope
• Provide water
• Contains water with
• allows diffusion to
dissolved salts, proteins
occur in cells
& other organic
compounds
Structure
• Double membrane of phospholipids
• inside stacks of discs called GRANUM
• contain:
– their own DNA
– ribosomes
– enzymes
Function
• photosynthesis (light energy
converted into chemical energy)
ATP + 6CO2 + 6H2O → C6H12O6 + 6O2
Granum= contains chlorophyll
which traps solar energy
Structure
• Tough, rigid outermost wall
• made up of cellulose (very strong)
Function
• maintains cell shape and skeletal support