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