Unit 2: Cells, Parts of Cell, Transport

Bio. 1.1

Understand the relationship between the structures and functions of cells and their organelles

Bio 1.1.2

Compare prokaryotic and eukaryotic cells in terms of their general structures (plasma membrane and genetic material) and degree of complexity

Unpacked:

•Proficiently use proper light microscopic techniques as well as determine total power magnification. The purpose is to use microscopes to observe a variety of cells with particular emphasis on the differences between prokaryotic and eukaryotic as well as plant and animal cells. While students are not expected to understand how scanning and electron transmission microscopes work, they should recognize that they reveal greater detail about eukaryotic and prokaryotic cell differences.

• Infer that prokaryotic cells are less complex than eukaryotic cells.

• Compare the structure of prokaryotic and eukaryotic cells to conclude the following:

· Presence of membrane bound organelles – mitochondria, nucleus, vacuole, and chloroplasts are not present in prokaryotes.

· Ribosomes are found in both.

· DNA and RNA are present in both, but are not enclosed by a membrane in prokaryotes.

· Contrasts in chromosome structure – circular DNA strands called plasmids are characteristic of prokaryotes.

· Contrasts in size – prokaryotic cells are smaller.

· Cells: are the basic unit of life

Cell Theory

1. All living things are made of cells (unicellular and multicellular)

2. Cell is the basic unit of life. Cell-> tissues-> organs -> organ system -> organism (This is the hierarchy)

3. Cells come from pre-existing cells.

· Viruses are exceptions. They are NOT living.

Robert Hooke: first scientist to use the term cell in biology. Used a microscope to view cells of a cork plant.

Microscopes: magnifies small objects so we can see them

· Total Magnification: Found by multiplying the eye piece by the objective

· To use a microscope

1. Use the lowest power objective first

2. Use the coarse adjustment bring the object into view. (large knob)

3. Then use the fine adjustment knob to focus the object. (small knob)

**** see worksheet of microscope for parts and functions

· Electron Microscope: Uses a beam of electrons and has greater magnification.

Two Types of Cells

Prokaryotic

Eukaryotic

No nucleus

Has a nucleus

Small in size

Complex, and big in size

DNA in center, makes chromosome AND circular DNA on outside (plasmid), NOT in a membrane

DNA in chromosome form, inside a membrane

No membrane bound organelles

Membrane bound organelles

Has Ribosomes

Has ribosomes

Always unicellular

Unicellular: (algae) or multicellular

Surrounded by plasma membrane

Surrounded by plasma membrane

Example: Bacteria

Examples: plant and animal cells

Label these parts on the prokarytic cell: DNA, plasmid, ribosomes, plasma membrane

Label these parts of the eukaryotic cell: nucleus, DNA, ribosome, plasma membrane

Look at the 4 cells to the left and classify them as eukaryote or prokaryote. Also, explain why you classified it the way you did.

1. ___________________________________________________________

2. ___________________________________________________________

3. ___________________________________________________________

4. ___________________________________________________________

Bio. 1.1

Understand the relationship between the structures and functions of cells and their organelles

Bio. 1.1.1

Summarize the structure and function of organelles in eukaryotic cells (including the nucleus, plasma membrane, cell wall, mitochondria, vacuoles, chloroplasts, and ribosomes) and ways that these organelles interact with each other to perform the function of the cell

Unpacked:

•Identify these cell organelles in diagrams of plant and animal cells.

• Explain how the structure of the organelle determines it function. (Example: folded inner membrane in mitochondria increases surface area for energy production during aerobic cellular respiration).

• Summarize how these organelles interact to carry out functions such as energy production and use, transport of molecules, disposal of waste, and synthesis of new molecules. (Example: DNA codes for proteins which are assembled by the ribosomes and used as enzymes for energy production at the mitochondria).

Cell Parts

· DNA - genetic material

· Cytoplasm: fluid part, makes up most of cell and organelles are found in it, lots of chemical reactions occur here

· Plasma membrane: maintains homeostasis in cell. Controls what goes in and out of the cell.

· Organelles: membrane structures found in cytoplasm, all have a special function

· Structure determines function: Folded membranes increase surface area and improves efficiency.

· Interact together to perform certain functions. (energy production and use)

Types of Organelles:

· Nucleus: controls all cell functions, holds DNA.

· Ribosomes: makes proteins, some free floating, some on ER

· Endoplasmic reticulum: synthesis or new molecules, ribosomes attached.

· Mitochondria makes energy (power house) double membrane

· Vacuole : stores food and water, small in animals, large in plants

· Golgi body: packages and sorts

· Chloroplast: makes food for plant cells, contains chlorophyll, site of photosynthesis, in plant cells only

· Cell wall: hard protection and support, surrounds plant cells, made of cellulose, in plant cells only

· Centrioles : aid in mitosis, in animals only

· Lysosome: digests waste for cell,

· Prokayotes and Eukaryotes both have: plasma membrane, cell wall, cytoplasm, ribosomes, and DNA

Can you think of some ways the organelles interact with each other?

Label the organelles below.

Types of organelles

Organelle

Function

Shape

Nucleus

Ribosome

Endoplasmic reticulum

Mitochondria

Vacuole

Golgi Body

Chloroplast

Cell Wall

Centriole

Lysosome

Plant VS Animal Cells

Plant Cells

Animal Cells

Have cell walls composed of cellulose

No cell walls

Are rectangular in shape

Are more round in shape

Have chloroplast with chlorophyll

Do not have chloroplast

Have larger vacuoles

Have small vacuoles

Label the cells as plant or animal then label the organelles.

A. ________________________ B.________________________ C. ________________________

D. ________________________ E. ________________________ F. ________________________

G. ________________________ H. ________________________ I. ________________________

J. _______________________

Plant or animal?

Plant or Animal?

1.2

Analyze the cell as a living system

1.2.1

Explain how homeostasis is maintained in the cell and within an organism in various environments (including temperature and pH).

Unpacked:

• Explain how cells use buffers to regulate cell pH and how cells can respond to maintain temperature, glucose levels, and water balance in organisms.

• Compare the mechanisms of active vs. passive transport (diffusion and osmosis).

• Conclude how the plasma membrane structure functions.

• Explain changes in osmotic pressure that occurs when cells are placed in solutions of differing concentrations.

4.2

Analyze the relationships between biochemical processes and energy use in the cell.

4.2.2

Explain ways that organisms use released energy for maintaining homeostasis (active transport).

Unpacking:

Conclude that energy production by organisms is vital for maintaining homeostasis and that maintenance of homeostasis is necessary for life. Examples: Active transport of needed molecules or to rid the cell of toxins; movement to avoid danger or to find food, water, and or mates; synthesizing needed molecules

Cell must: maintain homeostasis (steady state) at all times.

Cell Adaptations in Unicellular Organisms

· Unicellular organisms are made of one cell.

· Cilia: short hair-like projections from the membrane, aid in cell movement

· Flagella: Long whip-like structure that extend from membrane, usually 1 or 2, aid in cell movement

· Contractile Vacoule: helps remove excess water out,

· Eyespot: organelle that detects light

· Pseudopod: extensions of cytoplasm that are used to move as well as feed,

Label the structures below: Pseudopod, Contractile vacuole, Flagellum, Cilia

Most of the above structures live in aquatic environments. Why do you think that is?

How does the euglena use its contractile vacuole to maintain homeostasis? What would happen if it didn’t have one?

Cell Specialization

Cell specialization: cells throughout an organism can develop in different ways to perform different task. (differentiate)

· Stem Cells: undifferentiated cells that reproduce and have the ability to differentiate into one or more types of specialized cells. All cells originate from stem cells, instructions in the DNA lead to differentiation.

1. Embryonic stem cells: have the ability to become any type of cell

2. Adult stem cells: can only differentiate into certain types of cells

a. Bone marrow stem cells: become certain types of blood (RBC, WBC)

Cell Structure and Function

· Cells vary in size (longest is nerve cells)

· Cells vary in shape.

1. Red Blood Cells: round shape to travel easy through vessels

2. Xylem and Phloem in plants

· Xylem transports water, moves water up, larger than phloem

· Phloem transports sugar, moves sugar up, down, and sideways

3. Nerve cells: send messages to other cells through electrical impulses, also called neurons

4. Skin cells: flat and lost a lot, provide protection

5. Muscles cells: long flat cells with lots of mitochondria, and nucleuses

6. Sperm cells: head contains DNA with long tail

7. Egg cells: large and round

Example

What type of cell?

Level of organization (Hierarchy of living things)

Put these in order from smallest to largest:

Cell, organelle, DNA, tissue, organism, organ system, organ

Cell Communication

· How cells communicate or relay information to each other

· Short distance: cells that are close to each other can send molecules (messages) directly through cell membrane

· Nerve cells: electrical impulses (neurotransmitters) are sent from one nerve cell to the next.

· Long distance signaling through hormones: hormones are released from one cell and travels through the blood stream too the target cell. The target cell receives the hormone message via a receptor protein found in the cell membrane.

·

Which picture to the right is showing short distance communication?

Which one is showing long distance communications?

What are some similarities between the two?

Homeostasis: process by which organisms maintain a relatively stable internal environment.

Examples

·

· Regulation of Temperature

· Regulation of pH

· Toxin levels inside the cells

· Nutrient levels inside the cell

· Blood glucose levels

· Water regulation

The Plasma Membrane

Structure:

1. Phospholipid Bilayer:

· Phospholipid is made up of a phosphate with 2 fatty acid tails

· Fatty acid tails that are hydrophobic (afraid of water)

· Phosphates that are hydrophilic (love water)

2. Proteins

· Transport proteins allow substances to move through the plasma membrane.

· Chemical Markers (cell surface identity marker) helps cells to identify each other.

· Cell Signaling: messages from outside of cell are communicated to inside.

3. Cholesterol: Lipid gives stability to membrane

· Fluid Mosaic Model: fluid movement of phospholipids inside the membrane.

Plasma membrane structure

Hydro- phobic Tail

Hydro- phillic Head

Phospholipid Molecule

Function

· Protect inside of cell, provides a boundary

· Maintain homeostasis in the cell

· Selectively Permeable: Membrane allows certain molecules to pass through while keeping others out.

Transport Across The Membrane

Cell Transport: movement of material across the plasma membrane.

In solution:

· Solute - particles that are dissolved (sugar)

· Solvent - the substance in which the solute dissolves (water)

Concentration

· Amount of solute in a concentration

· High concentration = lots of solute

· Low concentration = low amount of solute

Concentration Gradient: means there is a difference in concentration across and area.

Types of Transport

Passive Transport

· Requires no energy

· Moves with the concentration gradient across the membrane, moves from an area of high concentration to low concentration

Examples:

Diffusion

· Movement of particles from an area of high to low concentration.

· Driven by the concentration gradient

· Goal: molecules to become equal throughout, reach equilibrium

· Examples: oxygen and carbon dioxide

Osmosis

· Diffusion of water through a semipermeable membrane

· Water moves from high to low concentration

Look at the diagram to the right:

The water molecules are moving to the right side of the membrane. This causes the water level to rise on the right side and go down on the left.

Facilitated diffusion

· Transport of large molecules by a protein in the membrane, Ex. Glucose

· Goal: to move large substances inside the cell that the cell needs

· Must us a channel protein

Osmosis

Cells in solutions:

Isotonic

concentration of dissolved materials is equal inside and outside the cell, water moves into and out of the cell equally, cell stays the same size

Hypertonic

concentration of dissolved materials is higher outside the cell than inside, water outside the cell and the cell shrinks

Hypotonic

concentration of dissolved materials is lower outside the cell than inside the cell, water moves into the cell and the cell swells

Label the pictures to the right as hypertonic, isotonic, or hypotonic

Draw an arrow on each picture to show how water is going to move.

How is water going to move in each of these:

Movement of water in animal and plant cells

Plant

· Plant cells contain a cell wall which protects them from bursting in a hypotonic environment, the pressure that builds up inside the cell is called turgor pressure.

· If placed in a in a hypertonic environment the cell doesn’t shrink but is can experience plasmolysis because the plasma membrane pulls away from the cell wall.

Animal

· Animal cells lack a cell wall, if they are placed in a hypotonic solution water will move in, causing the cell to lysis or burst.

· Special adaptation: paramecium have contain contractile vacuoles to pump out excess water.

Active Transport

· Requires energy

· Moves against the concentration gradient from low to high concentrations.

Examples

Carrier proteins

Proteins in cell membrane pump particles across the membrane using energy. Move the particles against the concentration gradient from low to high concentration.

Endocytosis

Process by which materials are engulfed by the cell. Endo: into the cell. Cell creates a vesicle to carry the materials

a. Pinocytosis: cell brings in fluids

b. Phagocytosis: cells bring in food or solid particles

Exocytosis

Process of materials leaving the cell. Exo = Exit