bio midterm 2 (lectures 11 and 12 and 13)

What is a cell?

the simplest collection of matter that can be alive- basic structural and functional unit of all living organisms

Cell Theory

1. all living organisms are made of cells

2. the cell is the fundamental unit of life

3. all cells comes from preexisting cells

3 Microscopy Terms

Magnification: how much larger an image appears compared with the actual object

Resolution: how clearly two close objects can be distinguished

Contrast: difference in brightness between light and dark areas

Light Microscope (LM)

• uses visible light and glass lenses

• magnifies up to 1,000x

• observes general cell structures of living cells

Scanning Electron Microscope (S.E.M)

• SURFACE

• uses beam of electrons on surface of specimen

• produces detailed, 3D surface image

• studies outside of structures

Transmission Electron Microscope (T.E.M)

• THROUGH

• passes electrons through specimen

• used to study internal cell structures

• highly detailed

Cell Fractionation

process that helps scientists separate different components of a cell

Cell Fractionation Steps

1. Cells broken apart (sonication)

2. Mixture placed in centrifuge

3. Centrifuge spins mixture

4. Cell components separate based on relative size

5. Scientist isolate different components to study

Purpose of Cell Fractionation

we can isolate an organelle and connect structure to function

Whats the difference between a prokaryotic or eukaryotic cell?

Prok have no nucleus and DNA is in the nucleoid region and Euk have a nucleus and DNA is found in nucleus. Prok have membrane-bound organelles

What are the 3 common bacterial shapes?

Cocci (spherical), Bacilli (rods), Spiral (corkscrew)

All cells share what 4 features?

1. Plasma membrane (separates cell from environment)

2. Cytosol (semifluid substance inside cell)

3. Chromosomes/Chromatin (contains genetic info)

4. Ribosomes (make proteins)

Plasma Membrane

separates the cell from enviornment with selective barrier

Phospholipid Bilayer

hydrophillic head and hydrophobic tail….arrange to form a barrier

Surface Area to Volume Ratio

Explains why cells are so small, surface area: membrane avaible for exchange and volume: internal space that needs resources and produces waste.

If there is a higher surface area to volume ratio…

there is more efficient exchange relative to cell volume

The Endomembrane System

membranes and organelles working together to regulate protein traffic and perform metabolic functions

The Nucleus

contains all of a cells genetic information

What are the nucleus’ main functions?

1. storing DNA

2. regulating cellular activities

3. controlling gene expression

Important Structures of Nucleus

1. Nuclear Envelope

   1. double membrane surrounding nucleus

2. Nuclear Pores

   1. regulate entry and exit of molecules

3. Chromatin

   1. DNA associated with proteins (less condensed)

4. Chromosomes

   1. condensed chromatin

5. Nucleolus

   1. produces ribosomal RNA (rRNA)

   2. inside nucleus

Ribosomes

protein factories…made up of rRNA and protein, carry out protein synthesis

Locations for Ribosomes

Free: in cytosol, make proteins that function inside cytosol

Bound: attached to outside of rough ER or nuclear envelope, make proteins that enter endomembrane system/become a part of membrane/secreted outside cell

Endoplasmic Reticulum

continuous with nuclear envelope

Rough ER

covered with ribosomes….functions include:

• producing proteins to secrete

• helping proteins enter endomembrane system

• producing glycoproteins

• creating transport vesicles

• acting as a membrane factory

Smooth ER

no ribosomes, functions include:

• lipid synthesis

• carbohydrate metabolism

• detoxification of drugs and poisons

• calcium ion storage, especially in muscle cells

Golgi Apparatus

shipping and receiving center made up of cistemae

Main Functions of Golgi Apparatus

• modified products from ER

• manufactures certain macromolecules

• sorts materials

• packages materials into transport vesicles

Cis-Face Golgi

receiving side…faces the ER

Trans-Face Golgi

sending side, faces away from ER (transSENDS)

How materials go through the Golgi

1. Proteins produced in the Rough ER

2. Placed in transport vesicles

3. Vesicles travel to cis face

4. Golgi modifies and processes proteins

5. Move to trans face

6. Golgi sorts and packs

7. New vesicles carry them to destinations

Lysosomes

membrane bound digestive compartments, hydrolytic enzymes break down, they have an acidic interior of aorun 5 pH

What do lysosomes break down?

protiens, lipids, nucleic acids, carbs, damaged components, materials brought into cell

Phagocytosis

when a cell engulfs large particles or another cell

Steps of Phagocytosis

1. cell surrounds and engulfs a particle like bacteria

2. particle is enclosed in Food Vacuole

3. Lysosome fuses with Food vacuole

4. Lysosomal Enzymes digest material

Autophagy

cell breaks down and recycles its own damaged molecules

Steps of Autophagy

1. Damaged organelles are enclosed in a vesicle

2. The vesicle fuses with a lysosome

3. Lysosomal enzymes digest damaged material

4. Components can be recycled by cell

What happens when lysosomal enzymes malfunction?

there is a build up and it can cause disease

Vacuoles

membrane bound compartments derived from ER and Golgi

Central Vacuole

stores water and organic compounds in mature plants cells

Food Vacuole

holds material brought into cell by phagotosis

Contractile Vacuole

pumps excess water out of cell

Lytic Vacuole

performs digestive functions similar to lysosomes

Peroximes…

single membrane organelles found in most eukaryotic cells.

Peroxime Functions

1. lipid metabolism

2. detoxification

3. breaking down certain metabolic byproducts

4. processing reactive oxygen species

What do peroximes do with Hydrogen peroxide

they turn it into water

The Complete Protein Pathway

1. Nucleus- DNA provides instructions to make proteins

2. Ribosome on rough ER- protein is synthesized

3. Rough ER- protein enters the ER and begins processing

4. Transport Vesicle- carries protein to the Golgi

5. Cis-face of Golgi- receives protein

6. Golgi- modifies, sorts, packs protein

7. Trans-face of Golgi- ships finished protein

8. Secretory Vesicle- carries protein towards plasma membrane

9. Plasma Membrane- vesicle fuses with membrane

10. Exocytosis- protein is released outside of cell

What is the main function of mitochondria?

site of cellular respiration, uses oxygen to generate ATP

Cristae

make up inner membrane folds of mitchondira, increases surface area for ATP producing enzymes

What is the main function of chloroplasts?

site of photosynthesis, found in plants and algae, captures light energy and helps produce sugars

Endosymbiont Theory

mitochondria and chloroplasts evolved from free-living bacteria engulfed by ancestral cells

Evidence for Endosymbiont Theory

both have double membranes, thier own circular DNA and ribosomes and reporoduce independently

3 components of a cytoskeleton

microtubules, microfilaments (actin), and intermediate filaments

Main Functions of Microtubules

support cell shape, move organelles, and separate chromosomes during cell divison

WHat do actin filaments and myosin do together?

produce movement, including muscle contraction and amoeboid movement

What are intermediate filaments responsible for?

reinforcing cell shape and holding organelles in place

How do cilia and flagella move?

dynein motor protiens move microtubules, causing the structures to bend