COL #2 - Cells/Units of Life, Structure and Function, Membrane Transport

Cells/Units of Life, Structure and Function, Membrane Transport

Cell Theory

• all living things are made of cells

• every new cell comes from the division of a pre-existing cell

Organelles that prokaryotes and eukaryotes share

• cell membrane

• cytoplasm

• ribosomes

• DNA

Why are cells limited in maximum size

if the cell gets too big, it can’t support itself

• surface area to volume ratio = dec rate of chemical change

Light microscopy

used in light microscopes to explore the structure and function of cells

Two different types of electron microscopy

TEM and SEM

What is TEM

Transmission Electron Microscopes

• electrons pass through the specimen

• produces a 2D picture

• reveals internal structures

What is SEM

Scanning electron microscopy

• electrons scan the surface

• produces a 3D picture

• reveals external structures

Characteristics of prokaryotic cells

• typically single celled

• no organelles

• DNA (circular) floats freely in cytoplasm

• unique cell walls

• much smaller than eukaryotic cells

• nucleoid

• most divide by binary fission

Characteristics of eukaryotic cells

• contain membrane bound organelles which each have specialized functions

• contains nucleus, DNA ribosomes, cytoplasm

• linear DNA

• divide by mitosis

T/F Eukaryotic cells contain a variety of membrane bound organelles, while prokaryotic cells do not

True

T/F All prokaryotic cells have a cell wall surrounding the membrane, while eukaryotic cells do not

True

What is the prokaryotic cell wall made of

peptinoglycan

What are eukaryotic cells’ nucleus surrounded by

nuclear envelope

What is the function of a nucleus

to store genetic material

Which are bigger - bacterial or animal cell

animal cell is bigger than a bacterial cell

What do animal and plant cells share

nucleus, ER, ribosomes, golgi apparatus, mitochondrion

What do animal cells have that plant cells do not

lysosomes

What do plant cells have that animal cells don’t

vacuoles, cellulose cell wall, chloroplasts

What organelle’s function is protein synthesis

ribosomes

What is the central dogma of molecular biology

DNA → RNA → Protein

What organelle is negatively and specifically affected by alzheimers

golgi apparatus

What is the function of the golgi apparatus

processes, sorts, and ships proteins synthesized through the rough ER

Endoplasmic reticulum

• site for lipid and protein synthesis (explains why parts are covered in ribosomes)

• like plumbing around the cell

• rough and smooth areas

What does lumen mean - in terms of the ER

the inside of any sac-like structure, like the ER

• this is where proteins are actually folded and processed

What is the smooth ER important for

important for detoxifying cells → needed in filtration organs

what does “cis” mean

receives

What does “trans” mean

ships/sends out

What are lysosomes

organelles that are full of digestive enzymes

• function: to break down and get rid of waste, recycle parts

What is autophagy and what organelle is it associated with

when lysosomes can digest large structures and organelles in the cytoplasm

• means “same eating”

What is a vacuole

a large membrane-bound structure found in plant and fungal cells

What are the functions of a vacuole

• most are used to store water and ions to help the cell maintain normal volume

• depending what kind of cell they are in, they can contain proteins and pigments

What is the cytoskeleton

a network of protein fibers around the cell

What are the functions of the cytoskeleton

• helps maintain structure/shape of the cell

• helps keep some of the organelles in place and allows others to move around

What are the different types of cytoskeleton

• microfilament

• intermediate filament

• microtubules

What are functions of microtubules

• maintain cell structure

• move cells

• move chromosomes during division

• provide pathways/tracks for intercellular transport

What important part of a cell is semipermeable

the cell membrane

How does oxygen move throughout the cell

simple diffusion

What aids in cell movement

cilia and flagella

What do flagella do

they propel the cell through whiplike/rotating motions

• generally longer than flagella

What do cilia do

move in coordinated back and forth motion

• generally shorter than flagella

• also more numerous

• can be found in the human trachea

Where can cilia not be found

cilia are not found in prokaryotes

What are the functions of the mitochondria

• extract energy from food

• convert energy into a useful form

Characteristics of the mitochondria

• found in eukaryotic cells

• double membrane

• has own ribosomes

• contains dna

What are chloroplasts

double membrane organelles

• have own DNA and ribodomes

• contains fluid (stroma) and membrane bound sacs (thykaloids)

What are antibiotics

chemicals that can slow or stop the growth of bacteria → used to fight bacterial infections

• weaken cell walls to penetrate cell

What is gram positive

group of bacteria

• contain cell wall with thick layer of peptidoglycan, which keeps a stain

• gives its purple color

What is gram negative

group of bacteria

• contains cell wall layer of peptidoglycan, which is surrounded by lipid membrane that does not retain the stain

• gives its pink color

What is the plasma membrane and its functions

the outer border of all cells and organelles; fluid mosaic structure which allows for flexibility

• controls what comes into and out of the cell

• adheres to other cells

What are the components of the phospholipid bilayer

hydrophilic heads and hydrophobic tails

What does hydrophilic mean

interacts well with water

What does hydrophobic mean

does not interact well with water

What types of transport can be done through the plasma membrane

active and passive transport

What type of transmission through the plasma membrane doesn’t require any energy

passive transport

Facilitated diffusion

large or hydrophilic molecules cross the cell membrane from high to low concentrations with the help of transporter protein, but without energy

What type of transmission through the plasma membrane requires energy

active transport (with ATP)

Active transport

moves substances against the concentration gradient

• requires energy

• ATP

What is simple diffusion

the natural tendency of dissolved substances to move from an area of high concentration to low concentration

• the simplest type of passive transport

• does not require energy

• stops when equilibrium is hit

What is osmosis

when water moves across the lipid bilayers

• moves from high water region to low water region

An outside solution with a higher concentration of solute is ______ to the inside of a cell

hypertonic

• water will move out, shrinking the cell

A solution with a lower concentration of solute is _____ to the cell

hypotonic

• water will move in, expanding the cell

What is it called when concentrations are equal on inside and outside

isotonic

• size remains the same

Protein channels

some are constantly open and others are gated

• embedded in plasma membrane

What is the conditionwhen you drink too much water

hyponatremia

Carrier proteins

specific to single substances

• bind to that substance and carry it to the other side of the gradient

Active transport

uses the help of transport proteins

• requires energy

• pumps solute into the side of higher concentration (against concentration gradient)

Primary active transport

moves an ion or molecules up its concentration gradient using energy from ATP hydrolysis

• different directions

Secondary active transport

pumps set up electrochemical gradients which powers to move against concentration gradient

• these gradients represent potential energy

• ATP not directly used

• same directions

What are the different types of carrier proteins/pumps used in primary active transport

• uniporter

• symporter

• antiporter

Uniporter

one molecule/substance enters

Symporter

two different molecules/ions are traveling through

• important that they are traveling in the same direction

Antiporter

two different molecules/ions are travelling through a channel but one is entering and one is exiting at the same time

What does coupled transport mean

energy derived from movement in one direction is used to drive other process

• used in symporters and antiporters

Sodium-potassium pumps

membrane proteins that provide active transport of molecules across the membrane

• uses ATP

• transports sodium and potassium against concentration gradients

• used in action potential process

What is bulk transport

a type of active transport that requires energy and is used when molecules/particles are too large to pass through a transport protein

What does “endo” mean

inside

Endocytosis

importing by bulk transport

• phagocytosis (cellular eating - surround and engulf)

• pinocytosis (cellular drinking - invaginates, pinches off)

• receptor mediated endocytosis (uptake of a specific substance is targeted by binding to receptors on the external surface)

Exocytosis

exporting by bulk transport