Ch 5 Flashcards by charlene gajudo

What does it mean to be amphipathic and give an example

Both hydrophobic and hydrophilic regions
Ex: phospholipids + membrane proteins

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What are lipid rafts

Proteins associated in specialized patches of lipids

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Membranes are held together mainly by __

Hydrophobic interactions

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Fluid mosaic model function

Acts for passage of things into and out of cell and communication between cells

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Some proteins are immobile; what does immobile mean?

Attached top cytoskeleton or extracellular matrix

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Membrane fluidity depends on __

Temp and saturation of fatty acid chains

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Difference between unsaturated tails and saturated in membrane fluidity

Unsaturated = prevent packing
Saturated = tails pack together

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Function of cholesterol in fluidity

Reduces fluidity at high temperature
Decreases temp for solidification

Fluidity Modulation: At lower temperatures, cholesterol prevents the fatty acid chains of phospholipids from packing too closely together, thus maintaining fluidity. At higher temperatures, it can help to restrain excessive movement, preventing the m

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How do lipid composition vary with colder and higher temp

Colder = more unsaturated phopholipids
Higher = unique lipids which decrease fluidity

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Embedded at least partially in hydrophobic region ___

Integral proteins

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Bound to the surface of the membrane

Peripheral proteins

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Membrane protein functions (6)

Intercellular joining
Attach to cytoskeleton and extracellular matrix
Enzymatic activity
Signal transduction
Cell-cell recognition
Transport

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Short branched carbohydrate chains used to create

Glycoplipids and glycoproteins

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Glycolipid and glycoproteins functions

Sort cells into tissues and organs
Recognition of self vs non-self: immune system

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Membrane layers differ in (2 things)

Lipid composition
Direction of inserted proteins

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Where and when is the arrangement of membrane lipids and proteins determined

During synthesis in the ER and GA

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Selective permeability meaning

Allow passage of some substance, but not others

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Is it easy for nonpolar molecules to dissolve in lipid bilayer and why

Yes
Nonpolar molecules share similar chemical properties with the lipid tails of the phospholipids, allowing them to integrate seamlessly into the bilayer. T

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How are ions and polar dissolve in lipid bilayer

Water crosses slowly and larger molecules even more slowly

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Meaning of passive transport

DOES not use energy

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How does substance concentration move in passive transport

High concentration to low

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What is the difference between diffusion and osmosis

Diffusion = movement of particles
Osmosis = movement of water

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Dynamic equilibrium meaning

Equal movement in either direction across membrane

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How does the movement of diffusion differ from osmosis in regards to concentration gradient

Diffusion = move from high to low region
Osmosis = move from high (low solute) water to low (high solute) water concentration

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Tonicity meaning

Ability of soln to cause cells to gain or lose water Tells us what happens to cell when they are put in different solution

3 diff solution in tonicity

1. Isotonic 2. Hypertonic 3. Hypotonic

This solution means the outside solution has the same amount of stuff (like salt) as the inside of the cell. Water moves in and out equally, so the cell stays the same.

Isotonic solution

outside solution has less stuff than the inside of the cell. Water moves into the cell, making it swell like a balloon, and it might even burst!

Hypotonic solution

When water moves out of the cell, cell volume decreases (shriveling, what is this process called

Crenation in RBCs

solution has more stuff than the inside of the cell. Water moves out of the cell, causing it to shrink like a raisin.

Hypertonic soln

What is this process called, when water enters cell and cell volumen increases = cell burts/lysess

Hemolysis

Osmoregulation meaning and examples

Ability of cells to protect themselves from extreme water loss/gain Paramecium Contractile vacuoles

What is turgor pressure

When cells with walls exert pressure back against water trying to move into a cell

Facilitated diffusion is aided by )___ and what does it mean

Transport proteins Span memb to allow passage of polar and charged molec and ions S

T or f, facilitated diffusion is not passive transport

False, it is bcs no energy input

___ channel that allows passage of polar and charged molec

Hydrophilic channel

__ channel that allow passage of specific ions

Ion channel,

what are carrier proteins and give one example

Bind to specific molec, ion, change shape and release on other side of the membrane Ex: glucose transporter

What is membrane potential caused by and what is its function

By uneven distribution of anions (-) and cations (+) This favours passive transport of cations into the cell and anions out

Electrochemical gradient is determined by

Both chemical gradient (concentration) and membrane potential (electrical)

Active transport meaning + characteristics

Moves substance against concentration gradient 1) involves carrier proteins 2) uses energy

A type of transport protein that produces voltage across a membrane as it moves ions

Electrogenic pump

Give 2 examples of electrogenic pump

1. Sodium potassium pump in animals 2. Proton pump in other organisms

Proton pump movement

Moving against chemical and electrical gradient Pumps hydrogen from internal to external Creating higher positive charge outside the cell

Cotransport meaning

Couples the transport one substance down its electrochemical gradient and one against

why is it called cotransport

Gradient created by hydrogen pump is often coupled with a transported for larger biomolecules

T OR F: bulk transport does not need active transport

False

Meaning of bulk transport + give 2 examples

Movement of large quantities across the membrane in vesicles (rather membrane proteins0 1) endocytosis 2) exocytosis

What is exocytosis and where is it formed

Contents released to external space = vesicles move to cell membrane, merge with it and release contents outside the cell Formed in golgi apparatus

Endocytosis meaning and give 3 kinds

Formation of vesicles from cell membrane for extracellular substances (bring materials into the cell) 1. Phagocytosis 2. Pinocytosis 3. Receptor-mediated

Phagocytosis function

Cell engulf (eat) external particle by extending pseudopodium around it Pseudopodium wrap around entire particle creating a food vacuole

In phagocytosis, where does food vacuole fuse to

Fuses to lysosome to digest contents

Pinocytosis meaning

Form of internalization in which vesicles are filled with extracelullar fluid Cell “gulps” up fluid Coated with proteins

Specialized form of pinocytosis which is specific to a certain substance is called

Receptor-mediated endocytosis

How does receptor mediated endocytosis work

Protein receptors bind to substance and are then internalized into the vesicle

Two major divisions of cell signalling

1) direct cell contact (local) - inhibits growth of cells (contact inhibition) - recognition of cell surface molecules (ex: immune system) 2) chemical signalling (local or long distance)

Long distance signaling uses __

Hormones

2 forms chemical signaling works

1) a chemical signal in extracellular fluid interacts w/ receptor of target cell 2) a chemical signal enters the cell and interacts w/ intracellular receptor

3 stages of cell signalling and give its brief meaning

1) reception: binding of chemical signal to receptors 2) transduction: series of stacking of chemical rxn 3) response: action that happens in the target cell

Molecule which binds to another molecule in reception

Ligand

Ligand binding results in __

Receptor activation & induction of a cascade of cellular events

Where is intracellular receptors located

In the cytoplasm or nucleus of the target cell

How does intracellular receptors work

by receiving signals inside the cell, interacting with DNA, and regulating gene activity to produce a specific response. = acts as transcription factors and carry out transduction part of the pathway

How does signal transduction work and what step is this and what does it allow

2nd step = this turns signal into a form that create specific cellular response = allows A) amplification B) coordination C) control of signal

Signal transduction involves the work of __ (3)

1. Protein kinases 2. Protein phosphatases 3. Secondary messengers

What does cellular response cause

1. Activation or deactivation of one or more cellular processes

What does cellular response regulate

Regulate 1) protein synthesis ( growth factors) 2) protein activity (metabolic enzymes)