NOTES for

Cell Structure & Function

Biology

2017

Johnson

I. Cells – the smallest unit of life

A. Discovery (“who’s who”)

1. Anton van Leeuwenhoek (B-Day: 10/24/1632)

a. scientist from the Netherlands

b. invented the microscope

c. Called the things he saw

“animalcules”

2. Robert Hooke (1665)

a. English scientist

b. Called spaces in cork “cells”.

3. Matthais Schleiden (1838)

a. Stated that all plants (and ONLY plants)

are made of cells

4. Theodor Schwann (1839)

a. discovered that all animals are made of

cells too

B. The Cell Theory (3 statements about cells):

1. All living things are made of cells.

2. Cells are the basic unit of structure and

function in living things. (ie: smallest

unit of life)

3. New cells are produced only from

existing cells by cell division (mitosis).

C. Differences in Cells

1. two main categories of cell types:

a. Prokaryotes

-no nucleus

-short, circular DNA called a “plasmid”

floats freely in cell

-bacteria only

b. Eukaryotes

-have a nucleus which holds the DNA

-everything except bacteria

(animals, plants, fungi, protists)

c. Viruses

-NOT a type of cell

-NOT a living organism

*cannot reproduce on their own

*just little bags of RNA in a

protein shell

D. All eukaryotic cells have 4 basic parts:

1. Nucleus - “control center” that holds DNA

2. Membrane - double layer of lipids around

cell for protection

3. Cytoplasm - “jelly” inside cell

4. Organelles - small structures inside cell that

perform specific jobs

E. Common Organelles in Cells PowerPoint

Animal Cell

Plant Cell

Nucleus *controls cell *holds DNA

Mitochondria *provides energy thru

cellular respiration

Cytoskeleton *fibers that give support

and structure to cell

Endoplasmic Reticulum *transports proteins from the

ribosomes to the Golgi

Ribosomes *assemble amino acids into proteins

Golgi *packages proteins and sends them out of cell

Cell Membrane *allows only certain things

into and out of cell Lysosome *cleans cell

Cell Wall *structure &

support for plant

Chloroplast *site of

photosynthesis

Vacuole *large empty space for storage of water

and C6H12O6

Nucleus

Mitochondria

Golgi

Lysosome

Endoplasmic Reticulum

Ribosomes

Cell Membrane

Cytoskeleton

F. Summary of Plant vs. Animal Cells

1. Plant Cells have…

a. Cell Wall – outside of membrane

-- support for plant

b. Chloroplasts – site of photosynthesis

-filled with chlorophyll.

c. Vacuole - storage area for glucose

produced by photosynthesis.

-takes up most of the cell’s

space.

2. Animal Cells

a. membrane without cell wall

b. no chloroplasts

c. no (or very small) vacuole

Notes: Protein Production & Transportation in a Cell

(start – 2:50)

II. Cell Specialization

A. Living things must do many things:

1. digestion

2. excretion

3. reproduction

4. movement

5. respiration

6. sensing

7. communication

8. healing

B. In unicellular organisms, a single cell must do

all of these functions.

C. In multicellular organisms, cells become

specialized to do particular jobs

1. The process of becoming specialized is

called “differentiation”.

2. We all start out as a single,

undifferentiated cell which can become

anything it wants to, called a “stem cell”.

3. At 10 days old the cells start to

differentiate (become specialized).

4. By birth, we are made of 100 trillion

cells which fall into 220 different types.

Ex) bone, skin, nerve, muscle, etc.

D. Stem Cells

1. cells that are not differentiated and can

become any cell type in your body.

2. two main sources of stem cells:

a. embryonic stem cells

conception-10 days old

controversial

b. adult stem cells

differentiated cells “backed up”

until undifferentiated

taken from any cell in your

body

III. Limits to Cell Size

1. As an organism grows, it gets MORE cells,

NOT bigger cells!

2. Two things allow a cell to get only so big:

a. Materials Movement

*nutrients and wastes need to get into and

out of the cell, and they only move so fast.

b. DNA overload

*the single copy of DNA in a cell’s

nucleus can only control so many

organelles!

IV. Levels of Cellular Organization

1. In multicellular organisms, the cells organize

themselves to accomplish complicated tasks.

2. The organization is in increasing complexity:

Cells-the basic units of life / 220 types.

Tissues-many of the same cells working

together to do a job.

Organs-several different tissue types working together

to do a job.

Ex) heart, stomach, kidney, etc.

Organ System-several different organs working

together to do a job.

*11 organ systems in our bodies

Ex) digestive system, respiratory

system, reproductive system

Organism-a complete, free-living collection of all the

organ systems.