What is a cell? Recall your work yesterday. When classifying...
Transcript of What is a cell? Recall your work yesterday. When classifying...
What is a cell? Recall your work yesterday. When classifying
cells, what are the two groups scientists separate cells into?
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 More advanced microscopes, like scanning and
electron transmission microscopes, allow us to see prokaryotic and eukaryotic cell differences in greater detail
Think about it: How does an electron microscope work? Why are these microscopes so expensive?
To find this, multiply the power of the objective lens (4X, 10X, 40X), by the power of the eyepiece (usually 10X)
Think about it: A student is viewing a slide using an objective lens with a power of 4X. What is the total power magnification?
4 x 10 = 40X
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!!!]
Think about it: How do a human and an elephant differ?
The elephant has more cells because it is larger, but the cells themselves are not bigger!
What do we know about 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.
1. All living things are composed of cells. 2. Cells are the basic units of structure and
function in living things. 3. New cells are produced from existing cells.
1. Which part of the microscope would you adjust to increase the magnification of a slide?
2. A student is viewing a slide using an objective lens with a power of 10X. What is the total power magnification?
3. What does the cell theory tell us about cells?
1. What is a cell? What does cell theory tell us about cells?
2. Think about what you know about cells. Name 5 organelles and their functions!
Prokaryotic
Simple Cells
Eukaryotic
Complex Cells
Plant and Animal Cells
Prokaryotic cells are smaller and less complex than eukaryotic cells No membrane bound
organelles; smaller Single-celled organisms
(ex. Bacteria) Contains: Single, circular
DNA; ribosomes; cell membrane
Eukaryotic cells are larger, complex cells made up of membrane bound organelles
Each organelle within the cell carries out different roles
Eukaryotic cells make up complex organisms (mostly multicellular)…like insects, fish, and mammals like you!
PROKARYOTIC
No membrane bound organelles (no mitochondria, nucleus, vacuole, or chloroplasts)
Ribosomes One strand of circular DNA
not enclosed in a nucleus Additional circular DNA
(plasmids) can be present Smaller size
EUKARYOTIC
Contains membrane bound organelles
Ribosomes DNA (enclosed by
membrane) DNA double-helix strands Larger size
Animal vs. Plant
Animal Cell
•Nucleus •Plasma Membrane •Mitochondria •Vacuoles •Ribosome •Cytoplasm •Lysosome
Plant Cell
•Nucleus •Plasma Membrane •Mitochondria •Ribosome •Cytoplasm •Vacuole (large) •Chloroplasts •Cell Wall
The “control center” Holds the DNA Dark spot inside
nucleus is called the nucleolus (it helps makes the ribosomes)
Nucleus
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
Think about it: Which cells would need a lot of mitochondria?
Think about it: What would happen if the cell lost all of its mitochondria?
The “gate” of the cell Double membrane
structure controls what comes in and out of the cell
“YOU SHALL NOT PASS” (without permission!)
Plasma Membrane
Protein producer The ribosome makes
proteins for the cell Can be attached to
the ER or free floating in the cytoplasm
Ribosome
“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
Jelly/gel A liquid/gel like
substance that surrounds the organelles
Cytoplasm
The “garbage cans” Break down and digest
waste products using enzymes
Lysosome
Think about it: what would happen to the cell if all of the lysosomes burst at the same time? Does this every happen on purpose?
“Supporter/protector” The cell wall shapes
and protects the plant cell
Cell Wall
Think about it: What is the plant cell made of? (Hint: What substance do plants make during photosynthesis?)
Food producers They are green Contain green chlorophyll
and trap energy from the sun for photosynthesis
Glucose (sugar) producers Produce enough ATP to
fuel photosynthesis
Chloroplast
All these organelles work together to keep the cell running!!
Think about it: What do you think would happen if…
The Mitochondria or Chloroplasts stopped working?
The Plasma Membrane didn’t do its job?
The Nucleus stopped directing activities?
Create a Venn diagram comparing eukaryotic and prokaryotic cells.
1. How are prokaryotic and eukaryotic cells similar? a) Both contain a nucleus
b) Both contain ribosomes
c) Both contain membrane-bound organelles
d) Both contain cell walls 2. This diagram shows a plant cell. Which structure is
found in a plant cell but absent in an animal cell? a) 1
b) 2
c) 3
d) 4
Identify the following descriptions as plant, animal or both:
1. Contains a cell membrane
2. Contains chloroplasts
3. Contains mitochondria
4. Contains lysosomes
5. Contains a nucleus
Label the parts of the cell:
1.
4.
5.
6.
8.
Which cellular process is most closely related the presence of chloroplasts in eukaryotes?
a) Metabolism
b) Photosynthesis
c) Aerobic respiration
d) Lactic acid fermentation
Nucleus “Brain of the cell”-controls cell functions and
stores DNA Mitochondria “Powerhouse of the cell”-makes energy through
cellular respiration; folded inner membrane provides lots of surface area for cell processes
Cell membrane “Gate of the cell”-Double membrane structure
composed of lipids-controls what goes in and out
Ribosomes
Site of protein synthesis (makes proteins); attached or free floating
Cytoplasm
Jelly/gel that surrounds cells-keeps organelles where they should be
Vacuole
“Storage center”-holds water, food, etc.-large in plants due to Turgor Pressure
Chloroplast
Plants only-uses sunlight to convert to sugar through process of photosynthesis
Cell wall
Plants only-carbohydrate called cellulose provides rigid structure that protects and supports cell
Lysosome
“Garbage can”-animals only. Uses enzymes to digest waste products
Endoplasmic Reticulum-Network of membranes that fold, modify, and transports proteins throughout the cell
Golgi Apparatus-receives proteins and lipids (fats); modifies, sorts, and packs them; works closely with the ER
Cells all begin as undifferentiated
Undifferentiated=not different; the same
DNA determines the type of cell (ex. nerve cell, muscle, blood…)
We will talk more about this later!
Mitochondria? Why? Chloroplasts? Why?
Cell organelles can be more concentrated
based on needs!
Candy Cells
Identify the following cell membranes by function:
1. Control center of the cell
2. Protective barrier for all cells
3. Storage organelle
4. Digestive organelle
5. Organelle responsible for making ATP
Decide whether the cell is plant or animal. Next, label the parts with the appropriate name.
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, euglena
Unicellular organisms have many structures that help them survive
Contractile vacuoles
Cilia
Flagella
Pseudopods
Eyespots
Stores excess water that enters the cell, and expels it to the exterior
It expands when filling with water, then contracts, expelling the contents back out
Found in: protists + unicellular algae
https://www.youtube.com/watch?v=pahUt0RCKYc
A dark area that functions in light reception; influences motion so that the organism can move toward/ away from light Toward (positive phototaxis)
Away (negative phototaxis)
Found in: green algae; photosynthetic unicellular organisms
Cilia Many hair like structures Often used for movement Non-motile cilia serve as
sensory organelles Flagella Single, whip like tail used
for movement Found in: bacteria,
protists, specialized plant, animal and fungi cells
https://www.youtube.com/watch?v=QGAm6hMysTA
Pseudopods
“False feet” that help the unicellular organism move about
Sometimes used to obtain food (phagocytosis)
https://www.youtube.com/watch?v=PsYpngBG394
Recall that “taxis” is an innate behavior in response to an outside stimuli
Movement in response to chemicals (“chemo”). Some single celled organisms direct their
movement according to chemicals in their environment
Found in bacteria and single-cell or multicellular organisms
Find food (e.g., glucose)
Flee from poisons (e.g., phenol)
Critical to early development
Movement toward or away from light. Many plant-like unicellular organisms will
move toward light to better photosynthesize, just like plants will tilt toward the window
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
https://www.youtube.com/watch?v=2koAGkgmiqg
Explain how a protest extends a pseudopod. How are cilia and flagella similar? How are
they different? Provide an example of a situation in which an
organism would exhibit negative phototaxis.
Identify the following cells: