Cell Structure

I will be able to understand the role of a cell. I will be able to identify the parts of a cell. I will explain the function of the various parts of the cell.

Cells have many different parts(organelles)

This and That about cells.

Cells are the basic unit(smallest part) of all living things.

If it’s alive, it’s made of cells! Cells hold all the biological

equipment needed to keep a cell alive and allow it to reproduce.

Unicellular organisms can’t grow very big.

Multi cellular organisms can grow big. Each cell is a specialist and has a special job to do.

Cell Membranes

All cells have them Flexible “bag”

covering that holds pieces and fluids inside and keeps nasty stuff out.

Permeable-means it has tiny holes that allow some things through. For example:oxygen

Some organelles have little membranes too!

Cell Walls

Only found in plants Made of special

sugars called cellulose

Help a plant keep it’s shape, allows them to grow bigger than animals

Also permeable, has small holes to allow nutrients through

Cytoplasm

Fluid that fills the cell Also called cytosol Organelles are

suspended in the cytosol

The cytoplasm has many different molecules dissolved in solution. You'll find enzymes, fatty acids, sugars, and amino acids that are used to keep the cell working.

Nucleus

The cell nucleus acts like the brain of the cell. It helps control eating, movement, and reproduction.

The nucleus is not always in the center of the cell.

Cell DNA is usually found here

Life Before a Nucleus

Not all cells have a nucleus. Biology breaks cell types into eukaryotic (those with a defined nucleus) and prokaryotic (those with no defined nucleus).

Ribosomes

Cells need to make proteins. Ribosomes are the protein builders or the protein synthesizers of the cell. They are like construction guys who connect one amino acid at a time and build long chains.

Ribosomes are found in many places around the cell. You might find them floating in the cytoplasm (cytosol). Those floating ribosomes make proteins that will be used inside of the cell. Other ribosomes are found on the endoplasmic reticulum.

Mitochondria

Powerhouses of the cell

Act like the digestive system-takes in nutrients, breaks them down, and creates energy-this is cell respiration

Mitochondria are small The number depends

on what the cell is doing. More can be created if needed.

Chloroplasts

Chloroplasts are the food producers of the cell. They are only found in plant cells and some protists.

They create the sugars the plant uses.(photosynthesis)

These are green and filled with chlorophyll

Endoplasmic reticulum

Works as a packaging system

Creates membranes throughout the cell

Works closely with Golgi apparatus and RNA

Looks different from cell to cell

Two types-rough ER and smooth ER

Same types of membranes, but different shapes and rough ER has ribosomes attached

Smooth ER acts as a storage organelle (steroids)

Rough ER packages proteins

Golgi Apparatus

Found in most cells Also a storage organelle Looks like rough ER but

has a very different function

The Golgi complex gathers simple molecules and combines them to make molecules that are more complex. It then takes those big molecules, packages them in vesicles, and either stores them

for later use or sends them out of the cell. It is also the organelle that builds lysosomes (cell digestion machines).

The Golgi complex is a series of membranes shaped like pancakes.

Centrioles

Organizes chromosomes Found near nucleus Not seen unless the cell

is dividing (mitosis/meiosis)

Every animal like cell has one

Made of 9 groups of microtubules

Found in pairs (usually at right angles)

Move towards the poles of the nucleus when it’s time to divide the cell

centrioles

Chromosomes

make organisms what they are. Carry all of the information used to help a cell grow and reproduce. Chromosomes are made up of DNA. Segments of DNA in specific patterns are called genes.

Found in nucleus of a cell. In prokaryotes, DNA floats in the cytoplasm in an area called the nucleoid.

Usually found in pairs

Vacuoles

Storage bubbles In plant and animal

cells, but much bigger in plants (as much as ½ the cell)

May store water, nutrients, or waste

Waste will be sent out of the cell

A membrane that surrounds a sac of fluid

In plant cells, this adds support

lysosomes

Found in nearly every animal like eukaryotic cell

Holds enzymes that the cell created

It’s purpose is to digest things Basically a vesicle filled with

enzymes The enzyme proteins are first

created in the rough endoplasmic reticulum. Those proteins are packaged in a vesicle and sent to the Golgi apparatus. The Golgi then does its final work to create the digestive enzymes and pinches off a small, very specific vesicle. That vesicle is a lysosome. From there the lysosomes float in the cytoplasm until they are needed.

Pili

Small tubes found on the outside of some prokaryotic cells (bacteria)

Adhesive and allows this cell to stick to other cells (thus spreading an infection)

Flagellum

Long whip like structure

Used for locomotion (movement)

Can be found in some prokaryotic and eukaryotic cells

Sometimes it is a sensory organ (can sense temperature and chemicals outside the cell)

cilia

Small,numerous projections that beat in one direction

Used for locomotion and sensory info

Found in a lot of animal cells, rare in plants

Similar to pili that can be found on prokaryotic cells

nucleoid

found in prokaryotic cells

Just a general region where genetic activity happens

No membrane around it