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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 membrane-
bound 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
Nucleoplasm
Chromatin
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
• large vesicle (but small in animals) and typically one large in plants
• Membranous sacs
Function
• 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
LYSOSOME ANIMATION http://highered.mcgraw-hill.com/olc/dl/120067/bio01.swf
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
• ‘Watery gel’ between cell membrane and nuclear envelope
• Contains water with dissolved salts, proteins & other organic compounds
Function
• Support & suspend organelles
• Provide water
• allows diffusion to occur in cells
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