Cell Biology

Zoljargal Chinbat

Plant biology

Cell biology is the study of cell structure and function,

and it revolves around the concept that the cell is the

fundamental unit of life.

Discovery of Cells 1665- English Scientist, Robert Hooke, discovered cells

while looking at a thin slice of cork.

He described the cells as tiny boxes or a honeycomb.

He thought that cells only existed in plants and fungi.

Anton van Leuwenhoek

1673- Used a handmade microscope to observe pond scum & discovered single-celled organisms

He called them “animalcules”

He also observed blood cells from fish, birds, frogs, dogs, and humans

Therefore, it was known that cells are found in animals as well as plants

Development of Cell Theory 1838- German Botanist, Matthias Schleiden,

concluded that all plant parts are made of cells.

1839- German physiologist, Theodor Schwann,

who was a close friend of Schleiden, stated that all

animal tissues are composed of cells.

Development of Cell Theory

1858- Rudolf Virchow, German physician, after

extensive study of cellular pathology,

concluded that cells must arise from preexisting

cells.

The Cell Theory Complete

The 3 Basic Components of the Cell Theory were

now complete:

1. All organisms are composed of one or more

cells. (Schleiden & Schwann)(1838-39)

2. The cell is the basic unit of life in all living things.

(Schleiden & Schwann)(1838-39)

3. All cells are produced by the division of

preexisting cells. (Virchow)(1858)

Modern Cell TheoryModern Cell Theory contains 4 statements, in addition to the original Cell Theory:

The cell contains hereditary information(DNA) which is passed on from cell to cell during cell division.

All cells are basically the same in chemical composition and metabolic activities.

All basic chemical & physiological functions are carried out inside the cells.(movement, digestion,etc)

Cell activity depends on the activities of sub-cellular structures within the cell(organelles, nucleus, plasma membrane)

Characteristics of all cells

Surrounded by cell membrane (plasma)

Contain DNA – genetic material.

Contain cytoplasm

Examples of Cells

Amoeba Proteus

Plant Stem

Red Blood Cell

Nerve Cell

Bacteria

Prokaryotic No nucleus (nucleoid

region).

Few internal structures - have simple ribosomes.

Smaller & simpler than eukaryotic cells.

One-celled organisms

Ex. Bacteria

Prokaryotic Cells Some use flagellum for locomotion

threadlike structures protruding from cell

surface Bacterial cell wall

Flagellin

Rotarymotor

Sheath

Eukaryotic Have a membrane bound nucleus,

control center that holds DNA (genetic material)

Contain organelles surrounded by membranes (small organs)

Most living organisms – lots of variety

Larger & more complex than prokaryotic cells

Eukaryotic cells

Diversity of Life

Unicellular Organisms 1 cell

Ex. Bacteria, Amoeba

Multicellular Organisms 2 or more cells

Ex. Plants & Animals

Levels of Organization Cells

Tissues

Organs

Organ Systems

Plant Cells vs. Animal Cells Plant Cells

Chloroplasts

Large Central

Vacuole

Cell Wall

Animal Cells

Lysosome

Centrioles

Organelles

Cell Membrane / Plasma Outer membrane of cell that

controls movement in & out of the cell

Double layer (Lipid Bilayer)

Plasma Membrane

Selectively permeable boundary between the cell and the environment

All cells have this!!

Cell Membrane / Plasma

Nucleus

Directs cell activities

Separated from

cytoplasm by nuclear

membrane

Contains genetic

material - DNA

Nuclear Membrane

Surrounds nucleus

Made of two layers

Openings allow material to

enter and leave nucleus

Chromosomes/Chromatin

In nucleus

Made of DNA &protein

Contain instructions for traits & characteristics

Contains instructions for making proteins

Nucleolus

Inside nucleus

Makes ribosomes

which then leave

the nucleus

Ribosomes

Each cell contains thousands

Make proteins (site for protein synthesis)

Found on Rough ER & floating throughout the cell

Endoplasmic Reticulum A system of tubes & sacs

formed by membranes (an enclosed space)

Moves materials around inside of the cell

Smooth: lacks ribosomes Lipid synthesis, drug

detoxifcation

Rough type (pictured): ribosomes embedded in surface Transports proteins to the

Golgi body

Golgi Bodies

Protein “packaging

plant”

Modifies protein

Attach lipids &

carbohydrates to

the protein

Vesicles move from ER to Golgi

Mitochondria Produces energy

through chemical reactions – cellular respiration

Converts glucose into ATP

Cristae – inner membrane

Matrix – inner membrane space

What is ATP?

Nucleotides

“Carry” chemical energy

from easily hydrolyzed

phosphoanhydride bonds

• Combine to form coenzymes (coenzyme A (CoA)

• Used as signaling molecules (cyclic AMP)

Lysosome

Digestive sac for proteins, fats, &carbohydrates

Transports undigested material to cell membrane for removal

Cell breaks down if lysosome explodes(A)

Cytoskeleton Network of protein fibers supporting cell shape and

anchoring organelles

Microfilaments

Actin

Cell movement

Support of cell

Microtubules

Hollow tubes

Movement of organelles

Forms cilia, flagella, centrioles

Cell membrane

Endoplasmic

reticulum

Microtubule

Microfilament

Ribosomes Michondrion

Cytoskeleton

Actin

Microtubules

Intermediate

filaments

Centrioles

Assemble

microtubules during

cell division

Barrel shaped –

pairs

Found In animal

cells (used during

cell reproduction)

Cell Wall

Most commonly

found in plant cells

& bacteria

Supports & protects

cells

Chloroplast

Found in plant cells

Contains green chlorophyll

Location where photosynthesis takes place in the cell

Vacuoles

Membrane-bound sacs for storage, digestion, and waste removal

Contains water solution

Help plants maintain shape- large central vacuole

“Typical” Animal Cell

“Typical” Plant Cell