Biol 190 Unit 2 Chapter 8

The study of cells=

The study of cells=

The study of life; life is continuous

What are the 3 parts of the cell theory?

1. Cells are fundamental units of life

2. All living organisms are composed of cells

3. All cells arise from preexisting cells

What are the two types of cells and its kingdoms?

1. Prokaryotic: cells do not contain organelles -Bacteria -Archaea

2. Eukaryotic: Plantae, Fungi, Protista, Animalia

What kingdoms are single-celled organisms?

Protists, Bacteria, Archaea, Protista, Fungi (a few)

What kingdoms are multi-celled organisms?

Animalia, Fungi, Plantae

Do larger organisms have larger cells?

No, larger organisms have more cells

Why are cells small?

High surface area : volume ratio

Cells must be large enough to...

House organelles and function

Cells must be small enough to...

Take in nutrients and take out waste to/from the entire cell

Cells have...

Varied size, shapes and functions; most cells are microscopic

What are light microscopes?

An optical instrument with lenses that bend visible light to magnify images of specimen

What specimens do light microscopes cover?

Living specimen (e.g. most plant and animal cells, nucleus, most bacteria, most mitochondrion); lower resolution than SEM and TEM

What is a scanning electron microscope (SEM)?

A microscope that uses an electron beam to look at the surface of a sample

What is a transmission electron microscope (TEM)?

A microscope that uses an electron beam to look at the internal structure of cells ( through the thin sections stained with metal atoms)

What are the structures present in all cells?

1. Plasma membrane

2. Semifluid substance called cytoplasm

3. Chromosomes (carry genes)

4. Ribosomes (make proteins)

What is a prokaryotic cell?

The first cell type on Earth; Unicellular (single-celled) with the following cellular structures:

-nucleoid region (where DNA is/ not an organelle)

+May Have:

- cell wall (tough outer structure)

-capsule (may surround the cell wall)

-flagella (rotates to move cell)

-fimbriae (used for attaching to surfaces)

When an organism has a membrane, cell wall, and capsule, it is...

Pathogenic

Do prokaryotes have cilia?

No

Prokaryotic vs. Eukaryotic:

-Prokaryotic: smaller, no nucleus/ organelles, one circular chromosome

-Eukaryotic: larger, extensive cytoskeleton, nucleus, membrane-bound organelles, multiple linear chromosomes

-Similarities: 1) DNA 2) Ribosome 3) Cytoplasm 4) Membrane

What is the predominant molecule in cell membranes?

Phospholipids

Are phospholipids water soluble?

No, they're a lipid

What are the four functions of the plasma membrane?

1. Physical isolation and protection

2. Regulation of exchange with the environment

3. Structural support

4. Identification

What is a fluid mosaic model?

A sheet of lipids with embedded proteins and attached carbohydrates

Define semi-permeable.

Some things can diffuse through the membrane, but not all

Phospholipids are _____________ molecules, containing hydrophobic and hydrophilic regions

Amphipathic

How do the phospholipids move?

Move laterally all the time, but do not flip flop due to the hydrophobic interactions

What factors affect membrane fluidity?

1. Lipid composition-> more unsaturation= more fluidity

2. Cholesterol

Which fatty acid type would create a fluid membrane? A viscous membrane?

Unsaturated fatty acids; saturated fatty acids

Would a thinner or thicker membrane result in better permeability?

Thinner-> things can move through a thinner membrane

What is embedded in the membrane?

1. Cholesterol- regulates membrane fluidity

2. Channel proteins- allow specific molecules to pass through

3. Receptor proteins- receive messages from other cells

What happens to membrane fluidity in cold temperatures?

Fluidity declines

What is the role of cholesterol in warm vs. cold temperatures?

-Warm: membrane= very fluid; cholesterol prevents gaps from forming in the membranes by pulling it together

-Cold: membrane=very viscous; cholesterol pushes the membrane apart

Up to ___% of the cell membrane may be cholesterol.

25

What are the types of membrane proteins?

-Peripheral proteins: on one side of the membrane, can be on the inside or outside (never embedded)

-Integral proteins: embedded (inserted) in the membrane; Two classes: partially embedded, transmembrane (all the way across)

-Transmembrane proteins: across the membrane, mimics the chemistry of the membrane. Inner part is hydrophobic; Outer part is hydrophilic

What is a glycolipid?

Carbohydrate covalently bonded to lipid, may serve as cell recognition particle

What is a glycoprotein?

Carbohydrate covalently bonded to protein

Where are membrane proteins synthesized in the cell?

ER

What are the six membrane protein functions?

1. Transport

2. Enzymatic activity

3. Signal transduction

4. Cell-cell recognition

5. Intercellular joining

6. Attachment to the cytoskeleton and ECM

What is a cell wall?

Extracellular structure that distinguishes plant from animal cells

What kingdoms have cell walls?

Bacteria, fungi, plantae (animal never have cell walls)

What is the function of the cell wall?

Protects the cell and maintains its shape

What is the primary component of a cell wall?

Cellulose- embedded in other carbohydrates and proteins

How do neighboring cells communicate?

Through adhering and communicating with direct contact

What are the cell junctions in animal tissues?

Tight junctions, desmosome, gap junctions, plasmodesmata

What is the first cell junction in animal tissues?

Tight junctions: membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid

What is the second cell junction in animal tissues?

Desmosomes: AKA anchoring junctions; fasten cells together into strong sheets; there is an intracellular space for movement of materials

What is the third cell junction in animal tissues?

Gap junction: (communicating junctions) provide cytoplasmic channels between adjacent cells

What is the fourth cell junction in animal tissues?

Plasmodesmata: channels that perforate plant cell walls, not found in animal cells (functions like straw); allow passage of water and small solutes (& sometimes proteins and RNA) from cell to cell

What are animal cells covered by?

Extracellular matrix (ECM):

-made up of glycoproteins such as collagen (fibrous), and other jelly-like substances

-hold cells together in tissues

-gives physical properties to cartilage, bone, etc.

-filters materials passing between tissues

What are integrins?

Link ECM to the membrane

Define cytoplasmic streaming.

Flow of the cytoplasm inside the cell

Define cytoplasm.

The material between the nuclear membrane and cellular membrane

Define cytosol.

The jelly like material between the nuclear membrane and cellular membrane