7.2 Cell Structure - Woodbridge Township School …...7.2 Cell Structure Cell StructureLesson...

Lesson Overview 7.2 Cell Structure

Lesson Overview Cell Structure

Cell Organization

– The eukaryotic cell

can be divided into

two major parts: the

nucleus and the

cytoplasm.

– The cytoplasm is

the fluid portion of

the cell outside the

nucleus.

– Prokaryotes do not

have a nucleus


Cell Organization

– Organelles “little

organs.”

– Example:

mitochondria, golgi

apparatus,

endoplasmic reticulum


The Nucleus

– the nucleus is the control center of the cell.

– It contains nearly all the cell’s DNA.


The Nucleus

– The nucleus is

surrounded by a

nuclear envelope

composed of two

membranes.


The Nucleus

– The nuclear

envelope is dotted

with thousands of

nuclear pores,

which allow

material to move

into and out of the

nucleus.


The Nucleus

– Proteins and RNA,

move through the

nuclear pores to and

from the rest of the

cell.


The Nucleus

– Chromosomes

contain the genetic

information that is

passed from one

generation of cells to

the next.

– They are found in

the nucleus.

– chromatin—DNA

bound to proteins.


The Nucleus

– a small, dense region in the

nucleus is called the

nucleolus.

– The nucleolus is where the

assembly of ribosomes

begins.


Vacuoles

– Vacuoles large, saclike, membrane-

enclosed structures

– They store water, salts, proteins, and

carbohydrates.


Vacuoles

In plant cells the pressure of the vacuole increases their

rigidity, making it possible for plants to support heavy

structures such as leaves and flowers.


Vacuoles

– The paramecium

contains an organelle

called a contractile

vacuole which pumps

excess water out of

the cell.


Vesicles

– Vesicles are used to store and move materials between

cell organelles, as well as to and from the cell surface.


Lysosomes

– Lysosomes are small organelles filled with enzymes that

function as the cell’s cleanup crew.

– Lysosomes remove “junk” that might accumulate and

clutter up the cell.

istockphoto.com


Lysosomes

– breakdown of lipids, carbohydrates, and proteins into

small molecules that can be used by the rest of the cell.


Lysosomes

– Break down organelles that have outlived their

usefulness.

Helps break down endometrial

lining of the uterus to cause

menstrual flow

Helps digest tissue to form

fingers in the fetus

http://www.babycenter.com/fetal-development-images-8-weeks


The Cytoskeleton

– Gives eukaryotic

cells their shape

and internal

organization.

– Microfilaments

and microtubules

are two of the

principal protein

filaments that make

up the

cytoskeleton.


Microfilaments

– Threadlike

structures made up

of a protein called

actin.

– Helps support the

cell.

– Help cells move.


Microtubules

– Hollow structures

made up of proteins

known as tubulins.

– Maintain cell shape.

– Important in cell

division.


Ribosomes

– small particles of RNA and protein found in the

cytoplasm; they produce proteins.

– The instructions to make proteins come from DNA.


Endoplasmic Reticulum

– internal membrane system of

the cell is known as the

endoplasmic reticulum, or

ER.

– This is where lipid components

of the cell membrane are

assembled, along with

proteins and other materials

that are exported from the cell.

– The ER is divided into smooth

ER & rough ER.


Rough Endoplasmic Reticulum or Rough

ER

– involved in the

synthesis &

modification of

proteins

– It is called rough

because of the

ribosomes found on

its surface.


Smooth Endoplasmic Reticulum or

Smooth ER

– Is called smooth ER

because ribosomes

are not found on its

surface.

– It contains enzymes

that make

membrane lipids and

the detoxify drugs.


Golgi Apparatus

– Proteins produced in the rough ER move to the Golgi

apparatus

– It appears as a stack of flattened membranes.


– It modifies, sorts, and packages proteins and

other materials from the ER for storage in the cell

or release outside the cell.

Golgi Apparatus


– From the Golgi apparatus, proteins are

“shipped” to their final destination inside or

outside the cell.

Golgi Apparatus


Organelles That Capture and Release

Energy

– The primary source of energy for plants is the SUN

– Your body cells get energy from food (plants and

animals).

– Chloroplasts and mitochondria are both involved in

energy conversion processes within the cell.


Chloroplasts

Plants and some other

organisms contain

chloroplasts.

Chloroplasts capture

energy from sunlight

and convert it into

food that contains

chemical energy.

CHLOROPLASTS are the biological equivalents

of solar power plants


Photosynthesis

Photosynthesis

process where plants

make carbohydrates

and oxygen using

sunlight energy,

carbon dioxide, and water.

http://www.phschool.com/scienc

e/biology_place/biocoach/image

s/photosynth/photo1.gif


Chloroplasts

– Two membranes surround chloroplasts.

– Inside the organelle are large stacks of other

membranes, which contain the green pigment

chlorophyll.


Mitochondria

– Nearly all eukaryotic cells, including plants, contain

mitochondria.

– Mitochondria are the power plants of the cell.

– They convert the chemical energy stored in food into

compounds that are more convenient for the cell to use.


Mitochondria

– Two membranes— an outer membrane and an inner

membrane —enclose mitochondria. The inner

membrane is folded up inside the organelle.


Mitochondria

– In humans, all or

nearly all of our

mitochondria come

from the cytoplasm of

the ovum, or egg cell.

You get your

mitochondria from

Mom!


Mitochondria

– Chloroplasts and

mitochondria contain

their own genetic

information in the form

of small DNA

molecules.

– The endosymbiotic

theory suggests that

chloroplasts and

mitochondria may

have descended from

independent

microorganisms.


Cellular Boundaries

– The barrier surrounding the cell is the cell membrane

– It (1) regulates what enters and leaves the cell and also (2) protects and (3) supports the cell.


Cellular Boundaries

– Plant cells and most

prokaryotes have a strong

supporting layer around

the membrane known as

a cell wall.

– The main function of the

cell wall is to provide

support and protection for

the cell.


Cell Walls

– Many prokaryotes,

plants, algae, and

fungi, have cell walls.

Animal cells do not

have cell walls.

– Cell walls lie outside

the cell membrane and

most are porous

enough to allow water,

oxygen, carbon

dioxide, and certain

other substances to

pass through easily.


Lipid bilayer

– It is a double-layered sheet found in nearly all cell

membranes.

– It gives cell membranes a flexible structure and forms

a strong barrier between the cell and its surroundings


Lipid bilayer

– Composed of

phospholipids

– The fatty acid portions

of such a lipid are

hydrophobic, or

“water-hating,” while

the opposite end of the

molecule is

hydrophilic, or “water-

loving.”


The Fluid Mosaic Model

– Most cell membranes contain protein molecules that

are embedded in the lipid bilayer.

– Carbohydrate molecules are attached to many of

these proteins.



– Fluid- because the

proteins in the lipid

bilayer can move

around and “float”

among the lipids.

– Mosaic- because so

many different kinds of

molecules make up

the cell membrane

MOSAIC

http://www.youtube.com/watch?v=LKN5sq

5dtW4

The Fluid Mosaic Model of the cell membrane

http://www.youtube.com/watch?v=LKN5sq5dtW4

http://www.youtube.com/watch?v=LKN5sq5dtW4



– Some of the proteins form channels and pumps that

help to move material across the cell membrane.

– Many of the carbohydrate molecules act like chemical

identification cards, allowing individual cells to identify

one another.



– If a substance is unable

to cross a membrane, the

membrane is said to be

impermeable to it.

– If a substance is able to

cross a membrane, the

membrane is said to be

permeable to it.

Although many substances can cross

biological membranes, some are too large

or too strongly charged to cross the lipid

bilayer.


– Most biological

membranes are

selectively

permeable, meaning

that some substances

can pass across them

and others cannot.

– Selectively permeable

membranes are also

called semi-permeable membranes.

7.2 Cell Structure - Woodbridge Township School …...7.2 Cell Structure Cell StructureLesson...

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