Chapter 4 Notes BIOLOGY

“The Cell”

4-1 CELLS Science is not static

World is flat Planets revolve around the Earth Only things that we can see, exist

1665 Robert Hooke- England: looked at a thin slice

of cork Where does cork come from? He saw chambers, and called them “cells” Why were the chambers empty?

1665… Anton Von Leewenhoek

Used a single lens microscope to observe pond water

He probably saw paramecium, euglena, and amoebas

Paramecium

Euglena Amoeba

                                                      

 Metaboly movements of Euglena.

Cells are the basic units of life

Cell Theory has 3 parts that are accepted by all scientists….

1. All living things are made up of cells 1838 Matthias Schleiden – all plants are

made of cells 1839 Theodor Schwann- all animals are

made of cells

2. New cells only come from other cells

1855 Rudolf Virchow said this …

3. Cells are the basic unit of structure and function of all living things.

Atoms are the smallest part that can exist alone

Cells are the smallest part that can exist alone and be considered “alive”

Technology: define each on yr own Fluorescent Labels Confocal Light microscope Hi Resolution Video Electron Microscope TEM SEM Scanning Probe microscope

Prokaryotes/ Eukaryotes

Cells: have a cell membrane, and

have DNA at some point in their lives

Prokaryotes-No nucleus

-Smaller-Have free floating DNA

-Bacteria-Can swim/ glide

Eukaryotes-Have nucleus

-Larger/complex-Specialized

-Some fd uni-cellular org-Some fd multi cellular org

4-2 Eukaryotic Cell Structure Organelles; the mini organs of the

cell

In the NUCLEUS

Nucleus- sends out instructions for making proteins “the brain”

Nuclear envelope- separates the nucleus from rest of cell

Nucleolus – dense region of the nucleus where manufacturing of proteins begin

Chromatin- DNA + protein Chromosomes- thickened chromatin that are

visible during cell division in nucleus

In the CYTOPLASM Ribosomes- where

proteins are assembled ER- where lipid parts

needed for cell membrane are made, also some proteins

Rough ER- is involved in making proteins, ribosomes are found on its surface Proteins made on these ribosomes, go into the rough er

and are modified Most proteins that are made here will be exported out of

the cell Smooth ER- contains collections of enzymes, ready

for action These enzymes perform specialized tasks like

detoxification of drugs Liver cells contain a lot of smooth ER ? Tylenol, alcohol

CYTOPLASM… Lysosomes: clean up crew

Filled with enzymes, that help digest proteins, lipids, carbs- “get the junk out of the cell”.

Tay Sachs Disease: these don’t function properly

Vacuoles Storage place for water, salts, proteins, carbs In plants, it is VERY LARGE, and holds water

and is under pressure – Making it possible for the plant to support structures like leaves and flowers

Paramecium has a contractile vacuole to pump out excess water

CYTOPLASM… Golgi Apparatus: (discovered by Camillo Golgi)

modifies, sorts and packages proteins, from the ER for storage or secretion outside the cell Customization, finishing touches are put on the

proteins- then they are packed and leave the factory

Mitochondria- “powerhouse” of the cell, converts chemical energy in food, to a compound the cell can actually use- Mitochondria has its own simple circular DNA In humans, Mitochondrial DNA is inherited from

your mom Your heart cells many mitochondria in each cell

Chloroplasts w/ chlorophyll Capture energy from sunlight, and convert it into

chemical energy Contain the pigment chlorophyll

Cytoskeleton: protein filaments that help maintain cell’s shape- also involved in movement Centrioles- help to organize cell division (stars) in

animals cells only Microtubules and filaments: help maintain cell

shape- help amoeba move

Flagellum/ Cilia- For movement or sweeping – respiratory tract Sperm cells

Cell membrane- both animals and plants Regulates what enters and leaves Provides some protection and support

Cell wall Present in plants, algae, fungi, and most

prokaryotes Porous enough to allow water, oxygen and carbon

dioxide among other substances through Fiber- and bowel movement Strong supporting layer made of cellulose a tough

carbohydrate fiber

Why don’t cells just grow bigger? Adults don’t have bigger cells than kids…

they just have MORE of them

The world's tallest man in 2007 7’9”,

Bao Xishun and his 5’6” wife…

most peoplewith acromegalic gigantism eventually die because of complications fromheart problems.

"Keeping the blood going round such an enormous circulationbecomes a huge strain for the heart,"

Why don’t cells just grow bigger?

DNA overload….DNA would need extra copies to handle “information demand”

Too difficult to get enough nutrients and oxygen IN and waste products OUT

What would happen?What would happen? Calculate ratio of surface area to volume

L * W * # of sides= surface area L * W * H= Volume Practice problem: if cell was a cube and its

sides were 1cm each ….figure SA? Figure V… What if the cell were 3cm? SA? V? What is the ratio?

Volume increases faster than surface area 1*1*6=6 SA 1*1*1=1 V Ratio 6:1

3*3*6=54 SA 3*3*3=27 V

Ratio 54:27 reduce… 2:1 The decrease in ratio of SA to V- makes it harder for

the cell to move needed products in and out.