Biol1090 Final Exam Flashcards

~3 billion years ago the Earths atmosphere was composed of

nitrogen, ammonia, methane, carbon dioxide, water and hydrogen gas

Lifes' organic building blocks were formed when

lightning bolts fuelled reactions that changed the composition of Earth's atmosphere

The method of the Miller-Urey experiment was

simulated Earths atmosphere from ~3 billion years ago then sent sparks of electricity through the system

The Miller-Urey experiment formed

urea, cyanide, formaldehyde and amino acids, the basic building blocks of life

The Cell Theory states that

- the cell is the structural unit of life
- all organisms are composed of one or more cell types
- cells can only arise by the division of a pre-existing cell

The production of a cell requires

information, chemistry and compartments

Compartments are

membrane bound structures dedicated to a particular function

The basic properties of cells are that they

- are highly complex and organized
- are actively controlled by a genetic program
can reproduce
- assimilate and utilize energy
- carry out chemical reactions
- engage in mechanical activities
- respond to stimuli
- are capable of self-regulation
- evolve

Prokaryotic cells are

structurally simple, ex: bacteria

Eukaryotic cells are

structurally complex

Types of eukaryotic organisms are

protists, fungi, plants and animals

Cells are organized with respect to

time and space

Viruses are

non-cellular macromolecule packages that can function and reproduce only within living cells

Virons are

inanimate particles that viruses exist as outside of cells

Virons are composed of

a small amount of genetic material and a protein capsule or capsid

The types of cells viruses can infect and the host range are defined by

the specific proteins on the cell surface

A virus with a wide host range is

rabies (dogs, bats, humans, etc.)

A virus with a narrow host range is

human influenza (epithelial cells of the human respiratory system)

Once a virus has infected a cell it

hijacks cellular machinery to synthesize nucleic acids, proteins and new virus particles

Lytic viral infections

rupture and kill cells by producing virus particles

Non-Lytic or integrative or lysogenic viral infections

- insert viral DNA into the host genome to create a provirus
- the cell can survive with impaired function

The function of biological membranes is to

- provide cell boundary
- define and enclose compartments
- control movement of material
- allow response to external stimuli
- enable interactions between cells
- provide a scaffold for biochemical activities

The Fluid-Mosaic model of biological membranes was named for

the way individual lipid molecules move and for the diverse particle that penetrate the lipid layer

The fluid-mosaic model is composed of

a bilayer of amphipathic lipids and proteins

The definition of amphipathic is

having both hydrophobic (non-polar) and hydrophilic (polar) regions

The phospholipids of biological membranes are composed of

a hydrophilic phosphate head and 2 hydrophobic hydrocarbon tails

Saturated hydrocarbon tails are

straight because every carbon has hydrogens so no double bonds need to form

Unsaturated hydrocarbon tails are

kinked because some of the carbons have formed double bonds with their neighbours because there are not enough hydrogens

Biological plasma membranes share properties such as

4-6 nm thickness, stable, flexible and capable of self assembly

Membrane composition determines

the membrane and the cells function

The inner mitochondrial membrane has a very high concentration of protein because

proteins are needed for making ATP with the electron transport chain

The myelin sheath has a very low concentration of protein because

fewer proteins make it easier to conduct nerve impulses

Integral membrane proteins

have a hydrophobic transmembrane domain that remains in the lipid bilayer

Lipid-anchored membrane proteins

are attached to a lipid in the bilyaer

Peripheral membrane proteins

associate with the surface of the lipid bilayer

Biological membranes are asymmetrical because

they have two leaflets with distinct lipid and protein composition
- the outer leaflet contains glycolipids and glycoproteins

Unsaturated lipids \____________ membrane fluidity

increase

Saturated lipids \____________ membrane fluidity

decrease

Increasing temperature \____________ membrane fluidity

increases

Decreasing temperature \____________ membrane fluidity

decreases

Membrane fluidity to crucial for

- mechanical support and flexibility
- dynamic interaction between membrane components
- membrane assembly and modification

When temperature changes biological membranes adapt by

desaturating lipids and exchanging lipid chains

Lipids in a membrane can move

- laterally within a leaflet
- or to the other leaflet

Movement of proteins in a membrane is

restricted because of space limitations

Cholesterol insertion into a liquid crystal membrane will

decreases fluidity

Cholesterol insertion into a crystalline gel membrane will

increase fluidity

Lipid rafts are

small areas of the plasma membrane that are enriched with certain lipids where some membrane proteins accumulate

The movement of small, uncharged particles across lipid bilayers is

relatively easy

The movement of large, polar/ charged particles across lipid bilayers is

not possible

Simple diffusion moves

small, uncharged particles with the concentration gradient

Diffusion through a channel moves

small, charged particles with the concentration gradient

Ion channels are

integral membrane proteins that select which ions can pass, they are often gated

Voltage-gated-channels respond to

changes in charge across the membrane

Ligand-gated channels respond to

binding of specific molecules (a ligand)

Mechano-gated channels respond to

physical force on the membrane

Facilitated diffusion requires

a facilitative transporter to bond to the integral membrane protein, changing its conformation and allowing the compound to move with the concentration gradient

Active transport uses

an active transporter the same way as facilitative diffusion, but it uses energy to move against the concentration gradient

The function of glycolax is to

- mediate intercellular interactions
- provide mechanical protection
- serve as a barrier to some particles
- bind to regulatory factors

Glycolax is

a bunch of carbohydrate groups attached to proteins and lipids in the extracellular space

The extracellular matrix is

an organized network of material produced and secreted by cells

The function of the extracellular matrix is to provide

- sites for attachment
- physical support
- regulatory factors (signals)
- definition between tissues

The extracellular matrix is composed of

proteins, glycoproteins and proteoglycans such as collagen, fibronectin and laminin

Plant cell walls are composed of

cellulose, hemicellulose, pectin and proteins

The function of plant cell walls is to

provide structural support to the cell and organism, protect the cell from damage and it contains biochemical signals

The endosymbiont theory is that

mitochondria and chloroplasts originated as aerobic bacterium that entered an anaerobic prokaryote and formed a symbiotic relationship with it

The outer mitochondrial membrane contains

enzymes and porins

Porins are

large channels that make the membrane permeable when open

The inner mitochondrial membrane contains

a high protein to lipid ratio (3:1), double layered folds called cristae and it is rich in cardiolipin phospholipids

The mitochondrial intermembrane space is

between the inner and outer mitochondrial membranes

The mitochondrial matrix has

gel-like consistency, ribosomes and DNA

Oxidative phosphorylation is

the transport of electrons to generate an electrochemical gradient which facilitates the synthesis of ATP

The first step of oxidative phosphorylation is when

- high energy electrons pass through conenzymes and electron carriers in the ETC
- the energy transfer facilitates the transport of protons into the intermembrane space, creating a concentration gradient

The second step of oxidative phosphorylation is when

protons are moved back into the mitochondrial matrix, generating enough potential energy to synthesize ATP in the matrix

Light-dependant reactions in chloroplasts

occur in the thylakoid membrane
- chlorophyl harvests the light, electrons enter the ETC and protons are pumped into the thylakoid lumen

Light-independent reactions in chloroplasts

occur in the stroma
- ATP produced in light reactions is used to make sugars

Apoptosis is

programmed cell death, regulated by the mitochondria

Apoptosis is characterized by

- the cell shrinking
- blebbing of the membrane
- fragmentation of DNA and nucleus
- loss of attachment to other cells
- engulfment by phagocytosis

Apoptosis is stimulated by

- intracellular stimuli which results in propoptotic proteins stimulating the mitochondria to leak apoptotic proteins

The endomembrane system involves the

ER, Golgi complex, lysosomes, vacuoles and endosomal transport vesicles

Green fluorescent protein (GFP) is

found in jellyfish and used to track the movement of proteins in the endomembrane system

Vesicular transport

moves materials between compartments

Transport vesicles are

small, spherical, membrane enclosed organelles that transport substances in the cell

Vesicular transport is broken into four steps

1) movement of the vesicle using the cytoskeleton and motor proteins
2) tethering the vesicle to a compartment by rabs and tethering proteins
3) docking the vesicle to a compartment by SNARE proteins
4) fusion of the vesicle to the membrane

Exocytosis is the

secretion of a substance (organelle -\> plasma membrane)

Endocytosis is the

absorption of a substance (plasma membrane -\> organelle)

The endoplasmic reticulum is

an inter-connected network of membrane-enclosed tubules and flattened sacs

The membrane of the ER is

continuous with the nuclear membrane

The function of the smooth is to

- produce steroid hormones
- detoxify
- store calcium

The function of the rough ER is to

- synthesize, modify and transport proteins
- synthesize membrane phospholipids
- glycosylate proteins
- fold proteins

The signal sequence on a protein is

several consecutive hydrophobic amino acids at the N-terminus of the protein

The purpose of protein signal sequences is

to direct protein synthesis to the ER

Cotranslational import is

the movement of the ribosome and mRNA to the ER membrane to complete translation

The first stage of cotranslational import is when

a signal recognition particle (SRP) binds to the signal sequence, stopping translation

The second stage of cotranslational import is when

the SRP binds to the SRP receptor which is embedded in the ER membrane

The third stage of cotranslational import is when

the SRP is released and the ribosome binds to the translocon for translation to resume

The fourth stage of cotranslational import is when

the forming polypeptide enters the ER lumen through the translocon as it is synthesized

After protein synthesis it has two options

1) It remains in the ER where it functions as a protein
2) It is transported to the Golgi complex for further modification and delivery to the secretory pathway

Some examples of proteins that undergo cotranslational import are

secretory and lysosomal proteins

Integral membrane proteins go through a modified form of cotranslational import that

the hydrophobic transmembrane sequences embed in the ER membrane

The ER-Golgi intermediate compartment (ERGIC) is

a region between the ER and Golgi where transport vesicles fuse to form larger vesicle and interconnected tubules that make up the cis-Golgi network (CGN)