unit 3 bio test

Prokaryotes

Are single-celled organisms that contain:

1. A cell membrane

2. Cytoplasm or cytosol

3. DNA but NO nucleus

4. Ribosomes: molecular machines that produce proteins

5. Does not contain organelles *

All are UNICELLULAR and carry out all of life processes

all bacteria (Archaebacteria or Eubacteria)

Eukaryotes

Usually larger and more complex (up to 10x wider and 1000x greater in volume)

- Genetic material is inside a nucleus

- Contains many internal structures & membranes (specialized organelles)

- Great variety! Examples include unicellular protists, algae, multicellular animals, fungi, plants

Endosymbiotic Hypothesis

Explains How Eukaryotic Cells Evolved from Prokaryotic Cells ~1.5 billion years ago

Steps to Endosymbiotic Hypothesis

- Simple Prokaryotic Cells acted as "Ancestral Prokaryote"

- Engulfed other Prokaryotic Cells

- Not destroyed or digested

- Both cells benefited, partnership (symbiosis)

- Plasma membrane folded in=nucleus

- Larger cell provided protection, and the smaller cells helped produce energy (mitochondria) or conduct - photosynthesis (chloroplasts).

- Became organelles

mitochondria and chloroplasts

What are the organelles in the Endosymbiotic Hypothesis

Nucleus

Function: Contains the cell's DNA and all instructions for making proteins

Structure: 3 Parts:

- Nuclear envelope

- Chromatin and Chromosomes

- Nucleolus

Nuclear envelope

Function: allow things in and out of the nucleus

Structure: 2 layers of membrane, cover the nucleus, contain small pores (or holes)

Chromatin and Chromosomes

Function: Heredity

Structure: Made of DNA material

Nucleolus

Function: makes ribosomes

Structure: Small, dense core

Cytoplasm

Function: provides structure to the cell

Structure: is the gelatinous liquid that fills the inside of a cell

Cell Membrane

Function: found in all cells and separates the interior of the cell from the outside environment=allows things in and out of cell

Structure: Made of a phospholipid bilayer

Cytoskeleton

Function:

- Forms the structure of a cell

- Organizes the interior of a cell

- Gives shape to cells without cell walls (like animal cells)

Structure: a network of protein cylinders and filaments

Ribosomes

Function: Make proteins

Structure:

- Made of RNA (rRNA)

- Found in the cytoplasm and the endoplasmic reticulum (rough ER)

Rough ER

Function: Protein synthesis, folding, transport

Structure: Contains ribosomes

Smooth ER

Function: Make lipids and hormones that help detoxify substances particularly drugs and alcohol

Structure: No Ribosomes

Golgi Apparatus

Function: Modifies, sorts, and packages molecules

Structure: Stack of membranes

Lysosomes

Function: The garbage and recycling center of the cell

Structure: Small sacs filled with enzymes to breakdown/recycle molecules

Vacuoles

Function: stores water, salts proteins and carbohydrates

Structure: Sac-like structure

- Plant cells have a single large one to store water

- Animal cells have smaller ones that assist with waste disposal

Mitochondria

Function: Convert chemical energy (food) into energy that can be used by cell (ATP)

in a process called cellular respiration

Structure: Surrounded by a double membrane and has its own circular DNA!

Chloroplasts

Function: capture energy from sunlight and convert it to food via photosynthesis

Structure: Found only plants and algae only and has its own DNA

- Contain chlorophyll

Cell Wall

Function: structural support and protection

Structure: Found only in plants and some prokaryotes

Cell membrane

Function:

- Regulates what enters and leave the cell

- Provides protection and support

Structure:

- Phospholipid Bilayer

- 2 layers of phospholipids

- Hydrophobic tails

- Hydrophilic Heads

Phospholipids

Maintains structural integrity

Cholesterol

Acts as a buffer and stabilizes the membrane

Peripheral proteins

Connecting points for the cytoskeleton and help transmit signals that come from outside the cell

Integral proteins

Serve as transport channels or pumps

Glycoproteins and glycolipids

Identification and cell-cell recognition

Passive Transport

- Moving Without Energy

- Movement of substances across the cell membrane without using energy from the cell.

- Examples: Diffusion, and Osmosis (special case of diffusion involving water)

Diffusion

- Small, nonpolar and some water

- Molecules can pass between phospholipids

Molecules move from areas of high concentration to areas of low concentration

- Move until concentration of molecules are equal = equilibrium

- Does NOT require any energy=PASSIVE

Osmosis

- Diffusion of water across a selectively permeable membrane

- Some membranes do not allow molecules to pass across = selectively permeable

- Water can move to help equalize the concentration if the molecules can't move

- Water moves from High to Low concentration

- Does not require energy = passive

Facilitated Diffusion

- Molecules move with the help of a carrier protein across the membrane

Types:

- Movement is from high to low concentration

- No energy is needed

Active transport

- Moves molecules from low concentration to high concentration

- Like pushing a rock uphill

- Against the concentration gradient

- Requires energy=ATP

- Usually uses protein pumps in the membrane

Isotonic solution

- Concentration of solutes is equal inside/outside of the cell

- Equal concentration

- Water moves in and out equally

- Cell size remains stable in animal cells; flaccid in plant

hypotonic

- Concentration of solutes is lower outside the cell than inside and water rushes in the cell

- Lower concentration in solution

- Higher concentration in cell

- Water moves in=cell swells

- Cell potentially explodes (lyses)

- In plant cell, cell swells = turgid

hypertonic

- concentration of solutes is higher outside the cell than inside and water rushes out of the cell

- Higher concentration in solution

- Lower concentration in cell

- Water moves out

- Cell shrinks or plasmolysis occurs

Cell Theory: Summary of the basic knowledge of cells

Modern Cell Theory:

1. All living things are made of cells

Cells are the basic unit of life

Can be unicellular or multicellular

2. New cells are made from

existing cells

3 scientists:

- Schleiden: 1838

Cells are basic unit of plants

- Schwann: 1839

Cells are basic unit of animals

- Virchow: 1855

All cells come from the division of pre-existing cells

Describe the cell theory. Include at least 3 scientists that contributed to the cell theory

Fluidity of Membranes

- Membrane fluidity depends on 2 types of fats

- Unsaturated Fats: (1 or more double bonds=kinks and more space) Fluid

- Saturated fats: (lack double bonds=straight and close) = viscous

- Can be altered by temp

Movement of Phospholipids

- Lateral Movement

- Side to Side within same layer

- Occurs often and rapidly

Flip flop

- Moves from one bilayer to the other

- Helped by enzymes: flippases, floppases, and scramblases

Cholesterol

- Acts as a buffer

Stabilize membrane

Fluid Mosaic Model

The cell wall is a rigid outer layer that provides support, protection, and shape to a cell. It is located outside the cell membrane. Is in plants, in fungi,and in bacteria. Animal cells do not have cell walls.

Describe the cell wall, including function, location, and molecular composition in different types of organisms.

Endocytosis

Moving material IN cell

- In folding of the cell membrane

- Phagocytosis: solid particles

- Pinocytosis: liquid particles

Example: Used to internalize nutrients and in gene therapy -

Exocytosis

Moving material OUT of cell

- Out folding of the cell membrane

Examples: Protein hormones like insulin or antibodies, enzymes, glycoproteins and neurotransmitters (chemical messengers in nerve cells)