Chapter 6

Cells

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Vocabulary

• cell: the basic unit of all living organisms

• organelle: structures inside of the cell that have different functions, means “little organ”

• nucleus: houses the genetic material of a cell

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Vocabulary

• unicellular: single celled

• multicellular: many cells

• membrane: a structure that encloses an organelle

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• Theory of Spontaneous Generation – the idea that non-living material produces life.–Aristotle - maggots come from raw

meat!

Theories of Life

• Francisco Redi – Italian Physician – 1668– Disproved part of spontaneous generation– Placed decaying meat in several jars, those

with screens over the top did not form maggots because flies could not land on the meat and lay their eggs.

Theories of Life

• Louis Pasteur – mid 1800’s– Created an experiment where he cleaned

the air of microorganisms and then allowed the air to mix with a broth containing nutrients – nothing grew because it was sterilized!

– Theory of Biogenesis – living organisms only come from other living organisms

Theories of Life

Theories of Life

Cell Theory• Three parts• 1. All cells come

from preexisting cells meaning cells divide to form new cells

• 2. All organisms are made up of cells

• 3. Cells are the basic unit of life

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Cells come from preexisting cells

All organisms are made of cells

Cells are the basic unit of life

Think about this!

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Cell Size

• Cells are small because they function more efficiently (better) that way

• Surface Area: Volume ratio– Smaller cells have more surface area

that stuff (volume) on this inside

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Cell Size

• Having more surface area allows more stuff to move into and out of the cells

• Cells get a lot of their nutrients and materials that way!

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Cell Size

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6:1 Means 6 times more surface area than Volume, 6 times more stuff can go through

2:1 Means only 2 times more surface area than Volume, 2 times more stuff can go through

***But the cells is bigger, so what do you think about the amount of nutrients it need?

So…

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Who has bigger cells?

Two Groups of Cells

• Eukaryotic: More complex cells

• Animal • Plant

• Prokaryotic: Less complex– Like bacteria

Prokaryotic Cells• very primitive cell• DO NOT have a

nucleus (DNA is loose)

• DO NOT contain membrane bound organelles

• Have ribosomes to make proteins

• unicellular (single celled)

Eukaryotic Cells• Have membrane bound organelles• Have a nucleus • More advanced than Prokaryotic

– Plant and animal cells

Cell Structure

• ALL cells have plasma (cell) membranes– Kind of like skin – surrounds the cell or organelles– Holds its shape

• Plant cells (Euk.) also have a cell wall which helps keep the plant upright

Inside the cells

• Everything inside the membrane is the cytoplasm– Includes

organelles if a Euk., and fluid

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Double Bubble Map

ProkaryoticCell

EukaryoticCell

Similar

Similar

Similar

Different

Different

Different

Different

Different

Different

Chapter 6

Cells

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Parts Inside the Cell

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Organelles• Means “tiny organ” in Latin. They are

small structures found inside the cell that carry out very important jobs within the cell

• Plant and animals cells have many organelles in common but they also have some that are unique to either the plant cell or the animal cell

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Membranes and Walls

• All cells have a plasma membrane that surrounds it– Selectively Permeably: regulates what

goes in and comes out of the cell

• Animal cells: cell membrane only• Plant cells: membrane and wall• Cell wall is tough and rigid

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Cytoplasm

• jelly-like substance and all organelles within the cell membrane

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Nucleus• The “Brain” of the cell, directs cell

activities

• Covered by a nuclear envelope membrane– Porous and allows materials in and out

• Contains most of the cells DNA– The DNA contain the information that

helps the cell function

Nucleolus- makes ribosomes

- in the center of the nucleus

Ribosomes

• Construct Proteins• bound to the Endoplasmic

Reticulum • or free floating

Endoplasmic ReticulumRough ER

– Covered in Ribosomes– package and export proteins made by

ribosomes– Looks like folded ribbon

• Smooth ER– No ribosomes– Makes lipids and exports them

Chapter 6

Cells

The Golgi Apparatus/ Body

• “UPS” of the cell • Modifies, stores, and routes

proteins and other products – Modifies by enzymes

• Looks like flattened stacks of pita bread

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Vesicle

• little packet of material created by the Golgi body to be “shipped” out

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Lysosomes

• Contain digestive enzymes• Break down old macromolecules for

reuse– DNA– Proteins– Polysaccarides

Mitochondria

• Power Station • Creates the energy (ATP) the cell

needs through cellular respiration• ATP: adenosine triphosphate

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Mitochondria

Vacuole

• PLANTS have a large central Vacuole– Helps with water balance– May contain poisons and pigments

Chloroplasts• Only in PLANT cells • Photosynthetic organelles

Cytoskeleton • Support skeleton for the cell

– Not entirely rigid and can change, unlike our skeleton

• Microtubules– Hollow tubes that provide rigidity and

shape– Act as tracks organelles can move on

• Microfilaments– allow for more movement

• Like oozing movement in amoebas

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Centrioles(Centrosome)

• help the cell’s genetic material move during cell division

• ANIMAL cells only!

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Structures for Cell Movement

• Flagella– Long and whip like– Used to propel the

cell– May rotate or whip

around to move

• Cilia – Shorter and more

numerous– Move in a back and

forth motion