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Chapter 7 Cellular Function and Structure Wasilla High School Mrs. Ragsdale 2014 - 2015
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Page 1: Biology chapter 7

Chapter 7

Cellular Function and

StructureWasilla High School

Mrs. Ragsdale

2014 - 2015

Page 3: Biology chapter 7

Cell Theory

All living things are made of cells

Cells are the basic unit of structure and life

Cells can only come from cells that already exist. They

have to receive DNA and pass it on to their offspring.

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How did cells become cells?

People used to believe in spontaneous

generation, the idea that life just came

into being all by itself.

While we now know that this isn't the

case, scientists still can't all agree on

exactly how the first cell came into

being

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Prokaryotic Cells: Bacteria

First cells

Small

Have no nucleus to house DNA

No membrane bound organelles (we'll talk more about this later)

Organelles – little specialized structures (like the nucleus) that have a specific function

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Eukaryotic Cells: Plants, animals and

other complex life forms

Much, MUCH larger than prokaryotic cells

More complex, evolved version of the cell

Contain membrane bound organelles

DNA housed inside the nucleus

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What do all cells need?

Plasma Membrane

Also known as the phospholipid bilayer

Made up out of phospholipids

Hydrophilic heads (water loving)

Hydrophobic tails (water hating)

Let's draw it! (Refer to page 188 in your

notes)

Page 8: Biology chapter 7

Fluid Mosaic Model

The protein channels, enzyme binding sites and cell recognition sites are able

to move around the plasma membrane like life rafts on a sea

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

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Selective Permeability

Selective means the ability to choose

Permeability means allowing things to pass

through

So…. Selective permeability means that the

plasma membrane can pick and choose what

passes through

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Passive Transport

No energy is expended

Diffusion = particles naturally move from a high to low

concentration gradient until equilibrium is reached

You want the same amount of particles on both sides of the membrane

Page 11: Biology chapter 7

Facilitated Diffusion What happens if the particles that want to cross the

plasma membrane are just too large to make it?

Using channels or carrier proteins to cross the plasma

membrane

No energy is used

Page 12: Biology chapter 7

Osmosis: Diffusion of Water

Water naturally is drawn to wherever high levels of Na+ and other

ions are

Osmosis is the movement of water across a membrane towards

the high level of concentrated ions

Page 13: Biology chapter 7

Tonicity

Hypertonic solution = more solute present outside of the

cells than what is inside

Water is drawn out of the cell

The cell shrivels

Hypotonic = less solute present outside of the cells than

what is inside

Water is pulled into the cell

The cell bursts (lyses)

Isotonic = the same amount of solute is present inside and

outside the cell

Water is balanced

Page 14: Biology chapter 7

Tonicity

Page 15: Biology chapter 7

Active Transport

Requires energy input

Sodium/Potassium

Pumps = requires ATP

to function

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Active Transport: Endocytosis and

Exocytosis

Transportation of large molecules

into and out of the cell

A small piece of the plasma

membrane pinches off and

becomes a carrier called a vesicle

The vesicle merges with the

plasma membrane and either

opens outside the cell (exocytosis)

or inside the cell (endocytosis)