Mcat Bio 1.w

Front 1

Why are cells so small?

Back 1

Cells must exchange materials with external environment via cell membrane, thus most cells are tiny because an increase in cell size would decrease the SA:V ration and decrease exchange.

Front 2

What does the fluid mosaic model of plasma membranes state?

Back 2

Phospholipid bilayer

Front 3

What does the endosymbiotic hypothesis state?

Back 3

Mitochondria developed from early prokaryotic cells that developed symbiotic relationship with eukaryotic ancestors

Front 4

What is the origin of zygotic organelles? What can be inferred from this regarding mitochondrial DNA?

Back 4

Maternal; all organelles identical to mother. Thus, any mitochondrial DNA a person has is identical to that of his/her mother.

Front 5

How do ribosomes differ as a function of protein destination?

Back 5

Proteins destined for cytoplasm synthesized by FREE RiBOSOMES, those destined for INSERTION into a MEMBRANE or SECRETION outside of cell synthesized by ribosomes bound to RER.

Front 6

How do prokaryotic ribosomes compare to eukaryotic ribosomes?

Back 6

Prokaryotic ribosomes are smaller than eukaryotic ribosomes.

Front 7

What is the lumen of the ER?

Back 7

Lumen = interior of ER, some portions are continuous with nuclear environment.

Front 8

What is glycosylation? Where does it occur?

Back 8

Addition of sugar group to proteins; mitochondria & ER

Front 9

Describe tight cell junctions.

Back 9

Membranes of neighboring cells attached such that no amterial can pass b/t cells or travel past jn (ex: intestine).

Front 10

Describe anchoring cell junctions.

Back 10

Found in cells subject to mechanical stress (ex: desmosomes in epithelial cells of skin)

Front 11

Describe gap cell junctions.

Back 11

Provide direct connection b/t cytoplasm of one cell and cyto of neighboring cells via channels.

Channels formed by CONNEXIN proteins (ex: heart--flow of ions through gap jns needed for rhythmic contractions)

Front 12

Do lysosomes bind the plasma membrane?

Back 12

No

Front 13

Where are ribosomes assembled? What is their general composition?

Back 13

Nucleus; mostly rRNA and to a lesser extent, protein. rrNA is synthesized in nucleolus and prots imported from cytoplasm.

Front 14

Do fungi classify as prokaryotes or eukaryotes?

Back 14

Eukaryotes

Front 15

How do fungi differ from plants?

Back 15

Fungi lack chloroplasts

Front 16

What are the two major groups of prokaryotes. Describe them.

Back 16

Archaea (methanogens, extreme halophiles, extreme thermophiles)

Bacteria

Front 17

What is the difference between gram + and gram - bacteria?

Back 17

Gram +: cell wall is thick and made of PEPTIDOGLYCAN

Gram -: cell wall it THIN layer of peptidoglycan SANDWICHED b/t layers of periplasm and coated with LIPOPOLYSACCHARIDE and PROTEIN LAYER

Front 18

How are cocci shaped?

Back 18

round/spherical

Front 19

How are bacilli shaped?

Back 19

rod-shaped

Front 20

How are spirilla shaped?

Back 20

Spiral-shaped

Front 21

What constitutes an obligate anaerobe?

Back 21

die in O2

Front 22

What constitutes a facultative aerobe?

Back 22

Survives with or without O2

Front 23

What constitutes an obligate aerobe?

Back 23

Needs O2

Front 24

What constitutes a photoautotroph?

Back 24

PS in plasma memebrane

Front 25

What constitutes a chemoautotroph?

Back 25

Energy obt'd from INORGANIC MOLECS (NH3, H2S)

Front 26

What constitues photoheterotrophs?

Back 26

Use light but require organic C-source (glucose)

Front 27

What constitutes chemoheterotrophs?

Back 27

Consume organic materials BOTH for energy AND a carbon source.

Front 28

How is prokaryotic mRNA polycistronic?

Back 28

single mRNA contains more than 1 coding region.

Front 29

Where do transcription and translation occur in prokaryotes? How does this differ in eukaryotes?

Back 29

In Prok: tx + tsln both occur in cytolpasm

In Euk: tx in nucleus, tsln OUTSIDE of nuc

Front 30

What is a genetic transformation?

Back 30

When DNA is incorporated into a recipient cell.

Front 31

Define transformation.

Back 31

DNA taken up from environment and integrated into bacterial genome.

Front 32

Define transduction.

Back 32

Bacterial genes transferred between bacterial cells via virus.

Front 33

Define conjugation.

Back 33

Genetic information directly transferred from one bacterial cell to another via PLASMIDS and temporary CONJUGATION BRIDGE

Front 34

Define generalized transduction.

Back 34

DNA from host's chromosome becomes part of viral genome, replacing viral genome randomly.

Front 35

Define specialized transduction.

Back 35

DNA from specific part of host's chromosome becomes part of viral genome, replacing SOME genes.

Front 36

What are Hfr cells and what is their significance in genetic transformations and mapping?

Back 36

Hfr = high frequency of recombination

Sometimes F plasmid integrated into bacterial genome such that during conjgtn entire CHROM replicates and moves through conj bridge.

Bridge usually breaks before transfer complete, but genes that make it through form novel genetic combos.

F plasmid ALWAYS first part to cross bridge, other genes go in same order. If interrupt conjgn at diff times, can determine order of genes on bact chrom.

Front 37

How do viruses determine what type of cells they can infect?

Back 37

Specific viral envelope proteins bind to cellular proteins in plasma membrane of host cell. Type of cellular prots in cell memb determine which viruses can bind.

Front 38

How do DNA viruses differ from RNA viruses?

Back 38

DNA: Viral DNA replicated and viral mRNA tx'ed within host's nucleus (or nuc region for prok). Some replicate and transcribe in cyto but bring own DNA and RNA polymerases.

RNA viruses: RNA rep'd and tx'ed in host's cytoplasm. RNA REPLICASE tx new RNA from RNA template and can be brought by virus or viral mRNA may code for it.

Front 39

What is a retrovirus?

Back 39

Viral RNA --> dsDNA--> Integrated with host genome

But don't usually go from RNA to DNA!! So usually has to bring REVERSE TRANSCRIPTASE to do this.

Since the virus is integrated into th genome, it is undetectable by the immune system (Ex: HIV).

Front 40

How do bacteriophage differ from TMV and the flu?

Back 40

Shape!
Bacphage = spider alien
TMV = rod
Flu = cottonball

Front 41

Describe the lytic cycle.

Back 41

bacteriophage hijacks host genetic machinery, assembles new phages, increased P on bact cel lwall and release of degradative enz lyse bact cell.

Front 42

Describe the lysogenic cycle.

Back 42

Viral DNA integrated into bact. genome (known as PROPHAGE form), remains dormant for a few generations, and either spont. or env factors, prophage sep from host genome and enter lytic cycle.

Front 43

Are fungi eukaryotes or prokaryotes?
What are their cell walls composed of?
Are they heterotrophs or autotrophs?

Back 43

Euk-->Memb bound organelles!
Cell walls = Chitin
Heterotrophs (lack chlorophyll!)

Front 44

How do fungi ingest nutrients?

Back 44

Release enzymes which break down complex molecules and then absorbs them from surroundings.

Front 45

Define hyphae.

Back 45

Filaments of multicelluar fungi.

Front 46

Define mycelium.

Back 46

Describes fungus as a whole.

Front 47

What is the environmental importance of fungi?

Back 47

Decompose wood and dead plant matter.

Front 48

Describe mushrooms.

Back 48

Filmentous, edible portion = fruiting body

Front 49

Describe molds.

Back 49

filamentous, IMPERFECT FUNGI (asexual)

Front 50

Describe yeast.

Back 50

Unicellular, use budding

Front 51

Describe lichen.

Back 51

Symbiotic jn of fungi and algea:
Fungi = ideal env for algael growth
Algae = PS = food

Front 52

How do fungi reproduce?

Back 52

Can be sexual or asexual. Early reproduciton usually asexual through sporangia/conidia (split off piece of fungus) and later on usually sexual.