Warm Up You will turn this in!

On the front of your paper, draw what you think a cell looks like. Label it if you would like.

On the back of your paper, write anything and everything that you know about cells (even if you think it may be wrong).

Warm Up

1. Write the equation for aerobic cellular respiration.

2. Explain what that equation means.

3. Write the equation for photosynthesis

4. Explain what that equation means.

The Cell: Structures and their Functions

The Cell

• The smallest, basic structural unit of all living organisms

• Different types based on what the organism is:– Bacteria: Prokaryotic cell– Animal: Eukaryotic cell, animal cell– Plant: Eukaryotic cell, plant cell

Prokaryotic vs. Eukaryotic

Prokaryotic and Eukaryotic CellsCharacteristic Prokaryotic Cell Eukaryotic Cell

Size

Nucleus

Membrane BoundOrganelles (MBO)

Cell Wall

Plasma Membrane

Chromosome Arrangement (DNA)

Small Large

Completely absent True nucleus, consisting of nuclear membrane & nucleoli

Absent (but has ribosomes)

present

Usually present; chemically complex

When present, chemically simple

Present, and chemically simple

Present; chemically complex

Simple chromosomes (PLASMID)

Complex chromosomes

• Scientists believe the prokaryotic cell evolved first because it is simpler than the eukaryotic cell.

• Example of a prokaryotic cell: bacteria

• Example of a eukaryotic cell: plant, animal, and fungi.

Plant vs. Animal Cell

PLANT• All organelles in

animal cell PLUS• Cell wall• Chloroplast

ANIMAL• Nucleus• Ribosome• Mitochondria• Vacuole• Plasma Membrane

Animal Cell

Plant Cell

Hierarchy of cells-Cells form a certain hierarchy:(From smallest to largest with example)1. Organelle – mitochondria, nucleus2. Cell – skin cell, liver cell3. Tissue – muscles4. Organ – liver, stomach, brain5. Organ system – digestive, endocrine6. Body – humans, fish, dogs, etc

Cell specialization:

• Not all cells are shaped the same. • They have different shapes to

accommodate their jobs.

Cell Types

Cell communication• Cells recognize one another• Chemical signals may be released by

one cell to influence the activity of another cell.

– Ex. a nerve cell can send a message to a muscle cell or to another nerve cell in response to something hot.

Homeostasis in the cell• Internal stability/equilibrium/balance• It is controlled by an organelle called

the plasma membrane (only allows some substances to pass.)

• The following needs to be maintained:– pH– Temperature– Salinity– Blood Glucose levels

How pH is maintained

• Through a buffer system• Buffer: a solution that has a stable pH

– When you add an acid to a buffer solution the buffer will neutralize it (cause it to become more basic)

– When you add a base to a buffer solution the buffer will neutralize it (cause it to become more acidic)

How temperature is maintained

• If cell needs to cool down: plasma membrane becomes more fluid to release heat

• If cell needs to heat up: plasma membrane becomes more rigid to keep internal heat from escaping

How salinity is maintained

• Through plasma membrane and a natural process called diffusion (will discuss more in depth later)

How blood glucose is maintained

• If blood glucose is low: body releases hormone (glucagon) to cause levels to rise

• If blood glucose is high: body releases hormone (Insulin) to cause levels to lower

• People with diabetes do not produce insulin so have trouble regulating blood glucose levels.

Warm Up

1. How is pH maintained in a cell?

2. Give one difference between a prokaryotic cell and a eukaryotic cell.

3. What 2 organelles are present in a plant cell but not present in an animal cell?

4. What type of cell (pro or eu) are plant and animal cells?

How a cell functions: ORGANELLES

• As a human, we wouldn’t be able to function without our organs (stomach, liver, kidney, pancreas, etc, etc, etc)

• A cell can’t function without its “organs” either. BUT a cells “organs” are called ORGANELLES

• Today we will review the most important organelles in a cell and their function

Organelle: Mitochondria• The “POWERHOUSE” of the cell• Function: provide energy to the cell

(cellular respiration)• How? Takes the food we eat and turns it

into the energy source (known as ATP)

Organelle: Mitochondria• How structure enhances its function:

– The organelle has two membranes (one protects the organelle, the other allows it to complete its task)

– The “folds” in the inner membrane (called cristae) increase the surface area inside the small organelle so that it can do as much work as possible!

Cell Part: Ribosome• Function: makes proteins through a process

called protein synthesis• 2 parts: large subunit and small subunit• How structure enhances its function:

– 2 subunits allow for protein synthesis (a very tedious/complex process) to be more simplistic

– More later…

Organelle: Nucleus

• The “CONTROL CENTER” of the cell• Function: contains all genetic information

(in the form of DNA) in the cell

Organelle: Nucleus

• How structure enhances its function:– DNA can NEVER leave the nucleus but we

need the DNA code to make proteins– The nucleus contains “pores” or holes on

the outer membrane– A material called “mRNA” that contains the

DNA code can leave through the pores to take the DNA message to the ribosomes so that proteins can be made.

Organelle: Vacuole• The “GARBAGE DISPOSAL” of the cell• Function: takes up waste or excess materials

from the cell (cellular digestion)

Organelle: Vacuole

• How structure enhances its function– Vacuoles in animal cells are small and there

may be multiple. In plant cells there is only one vacuole and it is extremely large

– Why? Plants can’t control the weather. If they get too much water, the vacuole takes it in and their volume will increase. If there is too little water, the vacuole will shrink and the plant will “droop”.

– Vacuoles help with plant rigidity

Cell Part: Plasma Membrane• The “GATEKEEPER” of the cell• Function: monitor what materials are going into

and coming out of the cell (cellular transport)• How? By use of phospholipid bilayer and

proteins

Cell Part: Plasma Membrane• How structure enhances its function:

– Small molecules coming into or out of the cell can pass through the spaces between the phospholipids.

– Larger/bulky molecules coming into or out of the cell can pass through with help from the embedded proteins

– More later…

Cell Part: Cell Wall

• ONLY FOUND IN PLANT CELLS!!!!!• Function: gives plant cell structure and

support• Made of cellulose...a carbohydrate

Organelle: Chloroplast• ONLY FOUND IN PLANT CELLS!!!!!!• Function: Photosynthesis (a process that

creates food in the form of sugars for the plant and creates Oxygen that is released into the atmosphere for animals to use)

Warm Up

1. What organelle is responsible for cellular respiration?

2. What organelle is responsible for cellular transport?

3. What is the purpose of photosynthesis?

4. Where does protein synthesis occur?

5. Why does the nucleus have pores?

TRANSPORT

Completed by the plasma membrane

Plasma MembranePlasma Membrane:

-Function: allows chemical substances to enter and leave the cell.-Structure: phospholipid bilayer and proteins

Why a phospholipid bilayer?• Phospholipids are both hydrophilic and

hydrophobic.• Heads are hydrophilic, tails are

hydrophobic• Bilayer forms because the tails are trying

to get away from the water

Why proteins?

• Proteins help move larger/bulkier molecules into and out of the cell.

• They are considered FACILITATORS

Types of Transport:1. Passive Transport- cell does not use energy (ATP) to move substances across the plasma membrane.

3 TYPES OF PASSIVE TRANSPORT:-Diffusion-Facilitated Diffusion-Osmosis

Diffusion and Osmosis• Diffusion: The net movement of particles

from areas of high concentration to areas of low concentration

• Osmosis: The same as diffusion but with water ONLY

Facilitated Diffusion

• Proteins provide a pathway for substances to pass through the membrane

2. Active transport- the cell uses energy (ATP) to move substances across the plasma membrane against the concentration gradient through a protein

Passive Transport Active Transport

Follows concentration gradient (high to low)

Goes against concentration gradient (low to high). Requires ATP (energy)

Materials are going towards equilibrium

Materials are not going towards equilibrium

Examples: Diffusion, osmosis, facilitated diffusion

Examples: excretion of waste products, sodium/potassium pump

Active transport example: Sodium/Potassium pump

• Sodium is SALT. You don’t want a lot of salt in your body.• You want potassium!• Our cells actively take in 2 molecules of potassium for every 3

molecules of salt (sodium) that it pumps out.• Requires energy (ATP) to complete this process.• Necessary because it keeps us healthy!

Video Review

https://www.youtube.com/watch?v=kfy92hdaAH0

Warm Up

1. What is the monomer of carbohydrates? Lipids? Proteins? Nucleic acids?

2. What are the use(s) of carbohydrates? Lipids? Proteins? Nucleic acids?

3. What type of organic molecule is cellulose?

4. What type of organic molecule is insulin?