When classifying cells, what are the two groups that scientists separate cells into?
What do scientists look for to classify the cell into one of the two categories?
Provide an example of a type of cell in each category.
Structure and Function of Living Organisms
A cell is the basic structural, functional, and biological unit of all living organisms
“The building block of life”
You are made up of about 37 trillion cells!!!
▪ In 1665, Robert Hooke used an early microscope to look at a thin slice of cork, a plant material.
▪ Cork looked like thousands of tiny, empty chambers.
▪ Hooke called these chambers “cells.”
▪ In 1838, Matthias Schleiden concluded that all plants were made of cells.
▪ In 1839, Theodor Schwann stated that all animals were made of cells.
▪ In 1855, Rudolph Virchow concluded that new cells were created only from division of existing cells.
▪ These discoveries led to the cell theory.
All living things are composed of cells.
Cells are the basic units of structure and function in living things.
New cells are produced from existing cells.
Eukaryotic
Complex Cells
Plant and Animal Cells
Prokaryotic
Simple Cells
Bacterial Cells
Prokaryotic cells are less complex than eukaryotic cells
No membrane bound organelles; smaller
Single-celled organisms (ex. Bacteria)
Eukaryotic cells are complex cells made up of membrane bound organelles
Each organelle within the cell carries out different roles
Eukaryotic cells make up complex organisms (multicellular)…like insects, fish, and mammals like you!
PROKARYOTIC
No membrane bound organelles (no mitochondria, nucleus, vacuole, or chloroplasts)
Ribosomes DNA in cytoplasm DNA forms a ring (ends are
connected) Cell are smaller in size Additional circular DNA
segments called plasmids
EUKARYOTIC
Contains membrane bound organelles
Ribosomes DNA in nucleus DNA double-helix strands
Cells are larger and complex
Prokaryotes Eukaryotes
Animal vs. Plant
▪ Organelles: Structures within a eukaryotic cell
that perform important cellular functions
▪ Atoms Molecules Organelles Cells
Animal Cell
•Nucleus •Plasma Membrane •Mitochondria •Vacuoles •Ribosome •Cytoplasm
Plant Cell
•Nucleus •Plasma Membrane •Mitochondria •Ribosome •Cytoplasm •Vacuole (large) •Chloroplasts •Cell Wall
The “control center” Holds the DNA DNA has coded instructions
for making proteins and other important molecules.
Dark spot inside
nucleus is called the nucleolus (ribosomes made here)
Nucleus
The ribosome makes proteins for the cell
Ribosome is made of protein and RNA
Does not have a membrane
Ribosome
The “powerhouse” of the cell
It produces most of the energy for the cell
Breaks down food to make ATP ATP is major fuel for all cell
activities that require energy
Folded inner membrane increase the surface area for energy production during respiration
Mitochondria
The “gate” of the cell It controls what comes
in and out of the cell “YOU SHALL NOT
PASS”
Plasma Membrane
Jelly/gel A liquid/gel like
substance that surrounds the organelles
Cytoplasm
“Storage tanks” of the cell
It stores food, water, and chemicals in the cell
Plant cell vacuole is much larger
controls Turgor Pressure
keeps plant upright
no water=wilting
Vacuole
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Vacuoles
Vacuoles are also found
in some unicellular
organisms and in some
animals.
The paramecium contains
a contractile vacuole
that pumps excess water
out of the cell.
Contractile vacuole
The “garbage cans” Break down and digest
waste products
Lysosome
Let’s pretend that the cell is a city. Which building would be
The nucleus?
The mitochondria?
The cell membrane?
In eukaryotes, the DNA is inside the nucleus. Why is this an advantage?
“Supporter/protector” The cell wall shapes
and protects the plant cell
Cell Wall
Food producers They are green Contain green chlorophyll and
trap energy from the sun and convert it into chemical energy
(photosynthesis)
Chloroplast
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Endoplasmic Reticulum
Ribosomes
Endoplasmic
Reticulum
There are two types of ER—rough and smooth.
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Golgi Apparatus
The Golgi apparatus appears as a stack of closely
apposed membranes.
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Cytoskeleton
Cytoskeleton
Ribosomes Mitochondrion
Endoplasmic
reticulum
Cell membrane
Microtubule
Microfilament
Plant Animal
Cells all begin as undifferentiated-DNA and genetics play a role in determining the type of cell (ex. nerve cell, muscle, blood…)
We will talk more about this later!
Light Microscopes and Total Power Magnification
We can use microscopes to observe cells in greater detail
Light microscopes are what we will use in class Advantage: See living organisms Disadvantage: Limited magnification
More advanced microscopes, like scanning and electron transmission microscopes, allow us to see prokaryotic and eukaryotic cell differences in greater detail Advantage: Higher magnification Disadvantage: Prep work requires dead organism
To calculate, multiply the power of the eyepice (usually 10X) by the power of the objective (4x, 10x or 40x, written on lens)
Example: A student is viewing a slide using an objective lens with a power of 4X. What is the total power magnification?
Eyepiece (10) x Objective (4) = Total 4 x 10 = 40X
Structure and Adaptations
A “multicellular” organism is composed of many cells (ex. You are composed of many animal cells; plants are composed of many plant cells)
“Unicellular” means they are composed of a single cell!
Ex. Bacteria, protozoa
Unicellular organisms have many structures that help them survive
Contractile vacuoles
Cilia
Flagella
Psuedopods
Eyespots
An organelle involved in regulating water
Pumps excess water out of cell
Found in protists and unicellular algae
Video Link
Shorter than flagella, located in large numbers Non-motile cilia:
Serve as sensory organelles Motile cilia: Beat in unison to move
a fluid past the surface of the cell Examples: ▪ Human Respiratory System:
Move mucus out of the lungs ▪ Human Reproductive System:
Move the ovum (egg) down the reproductive tract of females
Some unicellular organisms use cilia as method of movement
A whip-like structure that allows a cell to move
Found in
Bacteria
Protists
Specialized cells of plants, animals and fungi
Video Link
Temporary projections of cell membrane and cytoplasm
Purpose
Movement
Obtaining Food (Phagocytosis)
Found in Unicellular protists
Eukaryotic cells
Video Link
Organelle that senses light direction Swim towards light
(Positive phototaxis)
Swim away from light (Negative phototaxis)
Found
Green algae
Unicellular photosynthetic organisms
Taxis
Movement of an organism in response to a stimulus such as light or the presence of food
Innate behavioral responses.
Examples
▪ Chemotaxis
▪ Phototaxis
▪ Other examples
Chemotaxis the movement of an organism in response to a
chemical stimulus.
Found in bacteria and single-cell or multicellular organisms that direct their movements according to certain chemicals in their environment. ▪ Find food (e.g., glucose)
▪ Flee from poisons (e.g., phenol)
▪ Critical to early development
Phototaxis
Movement that occurs when a whole organism moves towards or away from light
▪ Photosynthetic organisms can orient themselves best to receive light for photosynthesis.
▪ Positive phototaxis: if the movement is in the direction of increasing light intensity
▪ Negative phototaxis: if the movement is in the opposite direction of light intensity
