BIOL 110 Lecture Exam 2

What is diffusion?

The movement of molecules across the membrane from an area of high concentration to an area of low concentration. (does not require cell energy)

The plasma membrane acts as a barrier that defines the cell and regulates the important process of ______________.

transport regulation

Polysaccharides found in the plasma membrane

what do they do?

Lysosome

An organelle containing digestive enzymes

Over time, hybrid cells show increasingly _______________ ________________.

intermixed proteins

Steps of determining what the membrane is mad of:

1. Counted RBCs 2. Calculated total SA 3. Destroyed the cells and collected the membrane phospholipids (chemical separation) 4. Placed the phospholipids into a chamber of liquid where they would form a floating monolayer 5. Measured the total SA of the phospholipids in the chamber, and compared it to the total SA of RBCs

Photobleaching Experiment

1. Labeled membrane proteins with fluorescent dye 2. Target an area of a plasma membrane and hit the cells with a laser, laser would destroy or bleach out the dye on an area of the membrane 3. See what happens

cell fusion experiment

1. The membrane proteins of humans and mice were stained with fluorescent dyes 2. Fused the cells together 3. Watched the colors over time, if the colors mixed or stayed locked in place

What is the ratio of a nuclear envelope membrane?

4:1

cytoplasm

A jellylike fluid inside the cell in which the organelles are suspended

flagellum

A long, hairlike structure that grows out of a cell and enables the cell to move.

cell wall

A rigid structure that surrounds the cell membrane and provides support to the cell

plasma membrane

A selectively-permeable phospholipid bilayer forming the boundary of the cells

pilus

A short, thick hair-like protein structure that allows a bacterium to attach to other bacteria and surfaces.

Chromatin

Clusters of DNA, RNA, and proteins in the nucleus of a cell

capsule

Covers the cell wall in prokaryotes.

If the membrane is a static structure and everything is locked into place, what would happen after lasering?

Everything would stay in place.

What was found with photobleaching experiments?

Fluorescent labeled molecules diffuse into bleached area.

look back at slides here

LOOK BACK AT SLIDES HERE

Cells are at a lower temp, how does PM change?

Membrane becomes less fluid, FA chains are shorter and more unsaturated.

Cells are at a higher temp, how does PM change?

Membrane becomes more fluid, FA chains are longer and more saturated.

Evert Gorter's experiment with red blood cells demonstrated what?

Membranes are composed of a phospholipid bilayer

Are things static in the plasma membrane?

No, they are dynamic structures.

Cell fusions experiments demonstrated what?

Plasma membranes are fluid.

endomembrane system includes

SER, RER, Golgi Complex, Vesicles

function of chloroplast

Site of photosynthesis, light energy is converted into usable chemical energy

inside the macrophage, ...

TB multiplies, kills and devours it, and spreads to infect more cells

What is active transport (anti-diffusion)?

The movement of molecules across the membrane from low concentration to high concentration. (requires cellular energy)

What was the most important reason that Dr. Gorter used red blood cells for his experiment?

They are uniform and identical, easy to get in large quantities, and easy to count.

How does the cell control membrane fluidity?

They change the fatty acid chains of phospholipids in two ways (happening simultaneously).

what do prokaryotes have that eukaryotes don't?

a cell wall

Cholesterol

a fluidity buffer of the membrane

fluid mosaic model of membrane structure

a model that describes the phospholipid bilayer as fluid and proposes that integral membrane proteins float freely in the lipid bilayer

structure of endoplasmic reticulum

a network of tubules and vesicles, walls composed of a lipid bilayer, space inside is the lumen

What is exocytosis?

a process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane. ex: insulin secretion

2 types of prokaryotic cells

archaea and bacteria

peripheral proteins

bound to the outer and inner surface of the membrane

How do we know that membranes are fluid?

cell fusion experiment (Johns Hopkins University)

both prokaryotes and eukaryotes have

cell membrane, cytoplasm, ribosomes

What do plant cells have that animal cells don't?

cell wall and chloroplasts

prokaryotes have a ________ _______ made of...

cell wall, peptidoglycans

DNA bound to protein (histones)

chromatin

the most distinctive feature of eukaryotic cells is their

compartmentalization

a semi solid gel (cytosol) contains all the cells internal components

cytoplasm

prokaryotes are small but they are the dominant life forms on earth in terms of

diversity and biomass

how does the nuclear envelope differ from plasma membrane?

double lipid bilayer

chloroplast structure

double lipid bilayer, enclosed within are internal membranes stacked into disks

mitochondria structure

double lipid bilayer, inner membrane is extensively infolded, fold are cristae, "liquid center" called the matrix

The plasma membrane is ____________ and cells can ______________.

dynamic, adjust

Primary lysosomes can digest material from outside the cell by fusing with an _________ or material from within the cell by fusing with an _________.

endocytic vesicle, phagosomes

outer bilayer is connected to

endomembrane system

Mitochondria function

energy metabolism: ATP production

Endocytosis is a process by which materials ______ a cell and Exocytosis is a process by which materials _____ a cell.

enter, exit

bacteria aka

eubacteria

cells that contain a membrane bound nucleus and an internal membrane system

eukaryotes

archaea aka

extremophiles

extracelluar fluid

fluid outside cells

secondary lysosome

fused with damaged organelle, digestive enzymes activated, toxic chemicals isolated

series of flattened sacs

golgi apparatus

stick of thylakoids

granum

Change 2: The cells can generate phospholipids that have...

have much longer or shorter fatty acid chains.

A major barrier for molecules crossing a plasma membrane is the _________________ ______________.

hydrophobic interior

For every cell type, there is an ______________ amount of fluidity.

ideal

The smooth and the rough ER are

interconnected with each other and the outer bilayer of the nuclear envelope

The plasma membrane's most basic function is

it acts as a barrier, keeping the outside out and the inside in

If the membrane is too solid...

it will not permit integral proteins to flex and carry out their functions.

If the membrane is too fluid...

it will not serve as a boundary and will fall apart.

What is simple diffusion?

jjj

Impermeable to what kind of molecules?

large polar molecules, ions

A saturated fatty acid chains means __________ fluidity.

less

The phospholipids with short FA chains are going to be packed _________ tightly. (more fluid)

less

What were the two possible outcomes for the lipid layer of the membrane?

lipid monolayer (1:1 ratio), lipid bilayer (2:1 ratio)

function of smooth ER

lipid synthesis, cholesterol and steroid synthesis, fatty acid desaturation

inactive insulin is

made in the rough ER

what is endocytosis?

material entering the cell, plasma membrane surrounds contents from around the cell, trapping it in an endocytosis vesicle

compartments are

membrane bound

Why are mitochondria and chloroplasts thought to have once been independent prokaryotic organisms?

mitochondria cannot arise from other mitochondria, circular dna, cellular division (endosymbiotic theory)

Endosymbiotc Theory

mitochondria only arise from pre-existing mitochondria

The extracellular matrix is made of

molecules secreted from cells

An unsaturated fatty acid chain means _____________ fluidity.

more

The phospholipids with long FA chains are going to be packed _________ tightly. (less fluid)

more

Change 1: The cells can generate phospholipids that have...

more or fewer unsaturations in the fatty acid chains.

primary lysosomes

newly formed lysosomes

Permeable to what kind of molecules?

nonpolar (and hydrophilic)

a double lipid bilayer membrane that surrounds the nucleus

nuclear envelope

endomembrane system includes

nuclear envelope, endoplasmic reticulum, golgi apparatus, lysosomes, vacuoles and the plasma membrane.

Parts of the nucleus

nuclear envelope, nucleolus, chromatin

passages through the nuclear membranes that regulate transport

nuclear pores

an area in the nucleus where ribosome complexes are assembled

nucleolus

What do prokaryotes lack?

nucleus and membrane bound organelles

compartments are called

organelles

Cells can change the ____________________ ___ ______________________ with saturated or unsaturated fatty acid chains.

percentage of phospholipids

Cell membranes are a ________________________ ___________________.

phospholipid bilayer

In the 1920's scientists knew that membranes were composed of ________________________.

phospholipids

functions of plasma membrane

physical barrier, transport regulation

A newly formed lysosome is referred to as a _______ lysosome and once it fuses with an endocytic vesicle or organelle the structure is referred to as a _______ lysosome.

primary, secondary

What does the cytoskeleton do?

protein fibers maintain the cells shape and can move the cell membrane

function of rough ER

protein synthesis bound for export from cell, or for use in the endomembrane system

function of golgi apparatus

proteins and other molecules may be modified and are sorted by eventual destination, packaged into vesicles

ribosomes are made of

rRNA and protein

cis face

receiving side of golgi apparatus

what important function occurs in the nucleolus

rewrite ribosomal rna

enzyme complexes that are considered organelles, non-membrane bound

ribosomes

the universal organelle, responsible for building proteins

ribosomes

trans face

shipping side of golgi apparatus

function of ribosomes

site of protein synthesis

ribosomes

site of protein synthesis

LESS permeable to what kind of molecules?

small polar molecules (size matters)

Endocytosis can be:

specific, using receptors, or passive, taking up water and nutrients

Functions of the nucleus

stores genetic info, site of ribosomes assembly, and RNA production

soluble material around granu

stroma

3 main functions of cytoskeleton

structural support, transport within the cell, help the cell move

Functions of the ECM

support (strengthens and cushions cartilage and bone), adhesion (hold cells together in tissue), movement, regulation (filters material between cells, ex: kidneys)

Integral (transmembrane) proteins

the majority of proteins; they extend entirely through the membrane

Red blood cells are _____________ in size.

the same

Tuberculosis bacterium survive and affect so many because

they are able to prevent phagosome/lysosome fusion, thus surviving and living in the cell.

single disks within the DLB of chloroplast

thlakoid