MCAT MILESDOWN BIOLOGY
COMPLETE STUDY GUIDE WITH
PRACTICE QUESTIONS AND VERIFIED
ANSWERS | GRADED A+ |
GUARANTEED SUCCESS
Updated 2026 Questions and Answers | 100% Verified
Exam Prep and Comprehensive Rationales Included
,plasmids -in prokaryotes
-carry DNA not necessary to survival
bacterial shapes bacillus (rod), coccus (sphere), spirillus (spiral)
obligate aerobe requires O2
obligate anaerobe dies in O2
facultative anaerobe toggle between aerobic/anaerobic
aerotolerant anaerobe does not use O2 but tolerates it
gram + purple, thick peptidoglycan/lipoteichoic acid cell wall
gram - pink or red, thin peptidoglycan cell wall and outer membrane
eukaryotes -electron transport chain in mitochondria
-large ribosomes
-reproduce via mitosis
prokaryotes -electron transport chain in cell membrane
-small ribosomes
-reproduce via binary fission
-plasmids carry DNA material, may have virulence factors
-plasmids that integrate into genome are episomes
prions -infectious proteins
-trigger misfolding (makes it go from alpha helical to beta pleated sheets)
-lowers solubility
viroid plant pathogen
microfilaments actin
microtubules tubulin
,intermediate filaments -keratin= vimentin
-desmin = lamin
types of epithelia -simple
-stratified
-pseudostratified
-cuboidal
-columnar
-squamous
simple one layer of cells
stratified multiple layers of cells
pseudostratified one layer but it appears as multiple
cuboidal cube shaped cells
columnar long and narrow shaped cells
squamous flat, scale like cells
connective tissue -stroma (support extracellular matrix)
-bone
-cartilage
-tendon
-blood
types of genetic recombination transformation, transduction, conjugation, transposons
transformation gets genetic info from environment
conjugation transfer of genetic info via conjugation bridge
-F+ -> F- or Hfr -> recipient
bacteriophage A virus that infects bacteria
-tail sheath injects DNA or RNA
, capsid protein coat surrounding a virus
envelope some viruses have lipid envelope
virion individual virus particles
viral genome may be DNA or RNA, single or double stranded
if single strand can be -positive sense: can be translated by host cell
-negative sense: RNA replicase must synthesize a complimentary strand which
can then be translated
retrovirus -single stranded RNA
-reverse transcriptase needed to make DNA
bacteriophage life cycles -lytic: virions made until cell lyses
-lysogenic: virus integrates into genome as provirus or prophage (goes dormant
until stress activates it)
cell cycle G1: make mRNA and proteins to prep for mitosis
G0: a cell will enter G0 if it DOES NOT need to divide
G1 checkpoint: cell decides if it should divide (p53 in charge)
S: DNA replicated
G2: cell growth, make organelles
G2 checkpoint: check cell size and organelles
M: mitosis and cytokinesis
positive growth signals 1) CDK + Cyclin create a complex
2) Phosphorylate Rb to Rb + P
3) Rb changes shape, releases E2F
4) Cell division continues
negative growth signals 1) CDK inhibitors block phosphorylation of Rb
2) So, E2F stays attached
3) Cell cycle halts
sex determined by 23rd pair of chromosomes
XX FEMALE
XY MALE
X-linked disorders Males express, females can be carriers
Y-chromsome little genetic info
SRY gene "sorry you're a male"
-gene on the Y-chromsome that lets male phenotype be expressed, absence of
SRY will lead to female phenotype
COMPLETE STUDY GUIDE WITH
PRACTICE QUESTIONS AND VERIFIED
ANSWERS | GRADED A+ |
GUARANTEED SUCCESS
Updated 2026 Questions and Answers | 100% Verified
Exam Prep and Comprehensive Rationales Included
,plasmids -in prokaryotes
-carry DNA not necessary to survival
bacterial shapes bacillus (rod), coccus (sphere), spirillus (spiral)
obligate aerobe requires O2
obligate anaerobe dies in O2
facultative anaerobe toggle between aerobic/anaerobic
aerotolerant anaerobe does not use O2 but tolerates it
gram + purple, thick peptidoglycan/lipoteichoic acid cell wall
gram - pink or red, thin peptidoglycan cell wall and outer membrane
eukaryotes -electron transport chain in mitochondria
-large ribosomes
-reproduce via mitosis
prokaryotes -electron transport chain in cell membrane
-small ribosomes
-reproduce via binary fission
-plasmids carry DNA material, may have virulence factors
-plasmids that integrate into genome are episomes
prions -infectious proteins
-trigger misfolding (makes it go from alpha helical to beta pleated sheets)
-lowers solubility
viroid plant pathogen
microfilaments actin
microtubules tubulin
,intermediate filaments -keratin= vimentin
-desmin = lamin
types of epithelia -simple
-stratified
-pseudostratified
-cuboidal
-columnar
-squamous
simple one layer of cells
stratified multiple layers of cells
pseudostratified one layer but it appears as multiple
cuboidal cube shaped cells
columnar long and narrow shaped cells
squamous flat, scale like cells
connective tissue -stroma (support extracellular matrix)
-bone
-cartilage
-tendon
-blood
types of genetic recombination transformation, transduction, conjugation, transposons
transformation gets genetic info from environment
conjugation transfer of genetic info via conjugation bridge
-F+ -> F- or Hfr -> recipient
bacteriophage A virus that infects bacteria
-tail sheath injects DNA or RNA
, capsid protein coat surrounding a virus
envelope some viruses have lipid envelope
virion individual virus particles
viral genome may be DNA or RNA, single or double stranded
if single strand can be -positive sense: can be translated by host cell
-negative sense: RNA replicase must synthesize a complimentary strand which
can then be translated
retrovirus -single stranded RNA
-reverse transcriptase needed to make DNA
bacteriophage life cycles -lytic: virions made until cell lyses
-lysogenic: virus integrates into genome as provirus or prophage (goes dormant
until stress activates it)
cell cycle G1: make mRNA and proteins to prep for mitosis
G0: a cell will enter G0 if it DOES NOT need to divide
G1 checkpoint: cell decides if it should divide (p53 in charge)
S: DNA replicated
G2: cell growth, make organelles
G2 checkpoint: check cell size and organelles
M: mitosis and cytokinesis
positive growth signals 1) CDK + Cyclin create a complex
2) Phosphorylate Rb to Rb + P
3) Rb changes shape, releases E2F
4) Cell division continues
negative growth signals 1) CDK inhibitors block phosphorylation of Rb
2) So, E2F stays attached
3) Cell cycle halts
sex determined by 23rd pair of chromosomes
XX FEMALE
XY MALE
X-linked disorders Males express, females can be carriers
Y-chromsome little genetic info
SRY gene "sorry you're a male"
-gene on the Y-chromsome that lets male phenotype be expressed, absence of
SRY will lead to female phenotype
