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