MCDB 6 Week 4-5

Light microscopes can magnify _______x

1000

t/f: organelles can be seen with light microscopy

F

Three parameters of microscopy

Magnification, resolution, contrast

What is magnification?

Ratio of an objects image size to its real size

What is resolution?

A measure of clarify of the image, minimum distance between distinguishable points

What is contrast?

Difference in brightness in light areas and dark areas

What are electron microscopes used for?

Studying subcellular structures

Two types of electron microscopes:

Scanning and transmission

What are scanning electron microscopes used for?

Studying the surface of a specimen

What are transmission electron microscopes used for?

Studying the internal structure of cells

What are fluorescent markers used for?

Labeling molecules to improve visualization

What is one type of microscopy that has helped sharpen images?

Confocal

What are the two processes involved in cell fractionation?

Sonication (breaking up cells) and centrifugation (separating components)

What can fractionation be used for?

Determining the function of organelles

Where is the DNA stored in a prokaryotic cell?

The nucleoid

What structure contains the cytoplasm of a cell?

Plasma membrane

What are the 4 basic features of ALL cells?

plasma membrane, cytosol, chromosomes, ribosomes

What structure forms the plasma membrane?

phospholipid bilayer

What feature of a cell dictates upper limits of cell size?

Metabolism

Equation of surface area and volume

surface area: n²

volume: n³

(smaller/bigger) cells have a greater surface area to volume ratio

smaller

In prokaryotic organisms, the PM is

encased in a rigid cell wall

What is the process by which prokaryotic organisms divide?

Binary dission

How do antibiotics work?

Selectively killing prokaryotic cells, leaving eukaryotic alone

How are animal cells different?

They have a centrosome

How are plant cells different?

They have cell wall, chloroplasts, central vacuole

What does the nucleus do?

Contains the genes

What is the nuclear envelope?

Encloses the nucleus and separates it from the cytoplasm

What is the nuclear membrane, what is it made out of?

Double membrane of lipid bilayer

What does the nuclear pore do?

Regulates entry and exit

What makes up chromatin?

DNA and protein

What does chromatin do?

Makes up chromosomes

Where is the nucleolus located?

In the nucleus

What happens in the nucleolus?

Ribosomal RNA synthesis

Where can ribosomes carry out protein sysnthesis?

Cytosol (free), ER (bound), nuclear envelope (bound)

What does the endomembrane system do?

Regulates protein traffic, performs metabolic functions

What are the components of the endomembrane system

Nuclear envelope, ER, golgi apparatus, lysosomes, vacuoles, plasma membrane

The components of the endomembrane system are either continuous OR

connected through transfer by vesicles

_____ accounts for more than half of the total membrane of eukaryotic cells

Endoplasmic reticulum

The endoplasmic reticulum is continuous with the ____

Nuclear envelope

Smooth endoplasmic reticulum ____

lacks ribosomes

Rough endoplasmic reticulum _______

has ribosomes

Functions of smooth ER

Synthesizes lipids, metabolizes carbs, detoxifies, stores calcium

Function of rough ER

Glycoproteins, transport vesicles, membrane factory

What makes up the golgi apparatus?

Cisternae

What are the functions of the golgi apparatus?

Modifies products of the ER, makes macromolecules, sorts materials into vesicles

What are lysosomes made out of?

Sac of hydrolytic enzymes, digest macromolecules

Lysosomal proteins are protected from digestion by lysosomal enzymes by

their 3d shape

What is phagocytosis?

Mechanism that cells use to engulf other cells and form a food vacuole

What is autophagy?

Lysosome recycles cell’s own dead organelles and macromolecules

Tay-Sachs Disease

Inherited lysosomal storage disease

What causes Tay-Sachs Disease?

Defect in an enzyme, lysosome unable to degrade glycolipids making them accumulate abnormally in brain cells

What can Tay-Sachs Disease cause?

Blindness, dementia, death

What are the groups with the highest risk for Tay-Sachs Disease

eastern european jews and french canadians

What is a vacuole

a large vesicle

Where are vacuoles derived from

the ER and golgi

What are the three types of vacuoles?

food, contracile, and central

mitochondria are the sites of _______

cellular respiration

the inner membrane of mitochondria folds into _____

cristae

What two things make up the inner membrane of the mitochondria

intermembrane space and mitochondrial matrix

What is the purpose of cristae?

providing a larger surface area for the enzymes that synthesize ATP

Chloroplasts are the sites of ______

photosynthesis

what pigment do chloroplasts contain

chlorophyll

What are peroxisomes?

Oxidative organelles (produce hydrogen peroxide and convert to water)

What is the endosymbiont theory?

an early ancestor of eukaryotic cells engulfed a prokaryotic oxygen using cell > merge into one organism (eukaryotic cell with mitochondria)

Similarities between miochondria/chloroplast and bacteria

double membrane, contain ribosomes + circular DNA, grow and reproduce independently

What is the cytoskeleton?

a network of fibers throughout the cytoplasm

organizes structures and provides support

What does the cytoskeleton interact with for motility?

Motor proteins

What are the three components of the cytoskeleton?

Microtubules, microfilaments, and intermediate filaments

What is the structure of microtubules?

Hollow tubes of globular proteins (tubulin)

What is the purpose of microtubules?

Shape, support, movement, separation of chromosomes during division

What is the structure of microfilaments?

Thin solid rods of actin subunits

What is the purpose of microfilaments?

Bearing tension to resist pulling forces

What is the purpose of intermediate filaments?

Reinforce shape and keeping organelles in place

What is the centrosome?

Location where microtubules grow out

What does the centrosome do?

organizes the microtubules

What are cilia and flagella?

Microtubule extensions projecting from cells

What is the motor protein that drives cilia and flagella?

Dynein

What is the ECM (extracellular matrix)?

covering of cells, made up of glycoproteins

What are the types of cell junctions?

plasmodesmata, tight junctions, desmosomes, gap junctions

what are plasmodesmata?

channels that go between plant cell walls so that solutes can pass between cells

what are tight junctions?

water tight seals between cells

what are desmosomes?

junction that anchors cells together

What are gap junctions?

Gaps between two cells so that materials can pass between them

Chloroplasts and mitochondria can synthesize some of their own proteins because ____

they have their own DNA and ribosomes

plasma membranes have _________ permeability

selective

Membrane proteins are ______

ampipathic

What is the fluid mosaic model?

cell membranes have proteins between the phospholipid to give it a fluid structure

The mosaic model allows proteins to

move around with the rearrangement of phospholipids

What is a glycoprotein?

protein with sugar attached

What is a glycolipid?

a lipid molecule with sugar attached

Unsaturated fats are more (solid/liquid)

liquid (double C=C bonds)

Saturated fats are more (solid/liquid)

solid, all hydrogen atoms present

What kind of lipid can wedge between phospholipids and alter membrane fluidity?

cholesterol

integral proteins

within the lipid bilayer

transmembrane proteins

span across the membrane and into the ECM

peripheral proteins

surface of the membrane

hydrophobic areas of proteins

contain non-polar amino acids (alpha helix secondary structure usually)

Membrane protein functions (6)

transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular signaling, attachment to cytoskeleton and ECM

Where does membrane synthesis begin?

Endoplasmic reticulum