MCAT BIOLOGY LATEST EXAMS SCRIPT QUESTIONS AND
ANSWERS SURE A+
✔✔Viral Life Cycle - ✔✔1. Infection: Bind to receptors, fusion, entry of virion.
Bacteriophage only inserts genetic material.
2. Translation and Progeny Assembly: Translation must occur in order for a virus to
reproduce. DNA viruses go to the nucleus, +RNA viruses stay in the cytoplasm, -RNA
needs synthesis of the +RNA via RNA replicase for translations. Proteins are created
and packaging then occurs.
3. Progeny Release: Released via initiation of cell death or lysing due to a large number
of virions. It can also be released via extrusion, or fusing with its plasma membrane and
budding essentially. Can also leave by extrusion, where the virus fuses with the plasma
membrane and forms a vesicle.
✔✔Lytic Cycle - ✔✔Bacteriophage makes maximal use of the cell's machinery with little
regard for the survival of the host cell. the bacteria are termed virulent.
✔✔Lysogenic Cycle - ✔✔Integration into the genome as a provirus or prophage.
Environmental factors will revert the provirus back to a lytic cycle.
✔✔Superinfection - ✔✔Simultaneous infection, usually prevented by lysogenic cycles.
Infection with one strain of phage generally makes it harder for the bacterium to be
infected with other phages.
✔✔Prions - ✔✔Infectious proteins that are nonliving things. Cause disease via
misfolding other proteins, usually causing the change from an alpha helical structure to
a beta helical structure. Protein aggregates form and cell function is reduced. Mad cow
disease!!
✔✔Viroids - ✔✔Small plant pathogens that consist of a very short, circular, single-
stranded RNA. They silence genes in the PLANT genome. HDV (hepatitis D virus) is an
example of a human viroid. Although alone HDV is harmless, when coinfected with
hepatitis B, HDV is able to exert its silencing function on human hepatocytes (liver cell).
✔✔Episomes - ✔✔Episomes are a subset of plasmids that are capable of integrating
into the genome of the bacterium
✔✔Positive Sense Viruses - ✔✔Implies that the genome may be directly translated to
functional proteins by the ribosomes of the host cell, just like mRNA.
✔✔Negative Sense Viruses - ✔✔These viruses require synthesis of an RNA strand that
is complementary to the negative sense RNA strand, which can then be used as a
,template for protein synthesis. These viruses must carry an RNA replicase in the virion
to ensure that this synthesis occurs.
✔✔Apoptosis - ✔✔Release of ETC enzymes
✔✔Autolysis - ✔✔Release of lysosome enzymes
✔✔Endosomes - ✔✔transport, package and sort materials to and from membrane. Can
send vesicles to:
1. Cell membrane for recycling
2. Lysosome for degradation
3. Golgi for transport or modification
✔✔Smooth Endoplasmic reticulum - ✔✔Smooth ER lacks ribosomes and is used for
lipid synthesis and detoxification of drugs and poisons. It also transports proteins from
the RER to the Golgi Apparatus.
✔✔HIV life cycle - ✔✔1. Proteins on the envelope bind to CD4 and CR5 on cell surface
2. Virus fuses with cell and empties content into cytoplasm
3. Reverse transcriptase converts RNA to DNA, making errors to generate diversity
4. Integrase inserts virus's DNA into host DNA
5. RNA polymerase converts DNA into RNA, ribosomes make proteins
6. Budding virus particle
7. Mature virus
✔✔Parenchyma - ✔✔Epithelial tissue constitute the parenchyma in most organs,
meaning they are functional parts of the organ (i.e. hepatocytes of the liver, nephron of
the kidneys). They are often polarized, one side faces the lumen, the other interacts
with blood vessels and structural cells.
✔✔Anaphase - ✔✔Centromeres split, each chromatid has its own distinct centromere
chromatids separate-via shortening of the kinetochore fibers.
✔✔Anaphase I - ✔✔Disjunction - each chromosome of paternal origin separates from
its homologue of maternal origin (either chromosome can end up in either daughter
cell).
The separating of the two homologous chromosomes is referred to as segregation.
This explains mendels law of segregation
✔✔Anaphase II - ✔✔Centromeres divide,
sister chromatids pulled to opposite poles.
✔✔Carriers - ✔✔females with a disease-causing X allele that do not exhibit the disease.
,✔✔Cell Cycle - ✔✔A series of specific phases in which the cell grows, synthesizes
DNA, and divides.
✔✔Chromatin - ✔✔less Condensed form of chromosomes during interphase. Makes
DNA available to RNA polymerase for transcription.
✔✔Corona Radiata - ✔✔Lies outside of the zona pellucida. Is a layer of cells that
adhered to the oocyte during ovulation. Meiosis II is triggered when a sperm penetrates
the corona radiata and zona pellucida via acrosomal enzymes.
✔✔Crossing Over - ✔✔homologous chromosomes break at synapsis, (called chiasma)
pieces of DNA are exchanged = recombination of genes.
Genetic diversity!
✔✔Cyclins and Cyclin-Dependent Kinases - ✔✔Molecules responsible for the cell cycle,
via fluctuating levels of cyclin. Cyclins bind CDK to activate them —> activated CDK-
cyclin complex phosphorylates transcription factors.
These then promise transcription of genes required for the next stage of the cell cycle.
✔✔Cytokinesis - ✔✔Separation of the cytoplasm/organelles -> daughter survive on own
✔✔Diploid - ✔✔(2n) contain two copies of each chromosome, 46
✔✔Ejaculation - ✔✔
✔✔roles of NS? - ✔✔When penis is flaccid, norepinephrine from Sympathetic NS is
present.
When sexual stimulation is present, the Parasympathetic NS causes release of NO
which causes Corpora Cavernosa/Spongiosum in penis to fill with blood=erection
Ejaculation meatus=contraction of muscle to expel sperm. The SNS is stimulated and
norepinephrine is released which causes contraction and release of semen into urethra
of penis. Sympathetic NS causes ejaculation, PNS causes erection!!
✔✔Female Sexual Development - ✔✔Ovaries are also under FSH and LH control. They
produce estrogen and progesterone.
Estrogens are secreted in response to FSH
—> the making/maintenance of reproductive system and secondary sex characteristics.
In embryo, they develop the repro. tract. In adults, E initially thickens the uterine lining
(endometrium).
Progesterone is secreted by the corpus luteum (remnant follicle that remains after
ovulation) in response to LH. Involved in development and maintenance of the
endometrium. End of 1st trimester, it's supplied by placenta.
, ✔✔Fertilization - ✔✔Sperm cell penetrates the layers with acrosomal enzymes,
triggering meiosis II. This indicates another meiotic division creating the mature ovum
and another polar body.
✔✔Follicle Stimulating Hormone - ✔✔In males, it triggers sperm maturation via Sertoli
cell stimulation.
In females, FSH causes estrogen to be produced
✔✔Follicular Phase - ✔✔Begins when menstrual flow, shedding of the uterine lining,
begins.
GnRH secretion from the hypothalamus increases in response to decreased estrogen
and progesterone.
Both FSH and LH increase in secretion —> development of follicles occurs
—> follicles produce estrogen, which (negative feedback) causes the decline of GnRH,
FSH, and LH.
Estrogen regrows the ENDOMETRIAL LINING, vascularizing and glandularizing the
decidua (uterine lining forming maternal part of placenta).
✔✔G0 Stage - ✔✔Normal cell/no division offshoot of G1 phase. Cell is simply living and
serving its function.
✔✔G1 Stage - ✔✔Create organelles - energy/protein production
increasing size.
governed by restriction points.
✔✔G1/S Checkpoint - ✔✔DNA good enough for synthesis? p53 protein is the main
control here. Known as the Restriction Point
✔✔If there is damage, cell arrests and p53 fixes problem. - ✔✔
✔✔G2 Stage - ✔✔Cell passes through another quality control checkpoint to ensure
DNA replicated correctly so error isnt passed down through M phase to progeny cells.
✔✔G2/M Checkpoint - ✔✔DNA of adequate size?
organelles replicate to support the daughter cells? (p53 protein plays a role here too.)
✔✔Haploid - ✔✔(n) contain one copy of each chromosome, 23
✔✔Head - ✔✔Covered by acrosome cap derived from Golgi apparatus and is
necessary to penetrate the ovum.
✔✔Hemizygous - ✔✔Only one copy of the X chromosome, ex: males.
ANSWERS SURE A+
✔✔Viral Life Cycle - ✔✔1. Infection: Bind to receptors, fusion, entry of virion.
Bacteriophage only inserts genetic material.
2. Translation and Progeny Assembly: Translation must occur in order for a virus to
reproduce. DNA viruses go to the nucleus, +RNA viruses stay in the cytoplasm, -RNA
needs synthesis of the +RNA via RNA replicase for translations. Proteins are created
and packaging then occurs.
3. Progeny Release: Released via initiation of cell death or lysing due to a large number
of virions. It can also be released via extrusion, or fusing with its plasma membrane and
budding essentially. Can also leave by extrusion, where the virus fuses with the plasma
membrane and forms a vesicle.
✔✔Lytic Cycle - ✔✔Bacteriophage makes maximal use of the cell's machinery with little
regard for the survival of the host cell. the bacteria are termed virulent.
✔✔Lysogenic Cycle - ✔✔Integration into the genome as a provirus or prophage.
Environmental factors will revert the provirus back to a lytic cycle.
✔✔Superinfection - ✔✔Simultaneous infection, usually prevented by lysogenic cycles.
Infection with one strain of phage generally makes it harder for the bacterium to be
infected with other phages.
✔✔Prions - ✔✔Infectious proteins that are nonliving things. Cause disease via
misfolding other proteins, usually causing the change from an alpha helical structure to
a beta helical structure. Protein aggregates form and cell function is reduced. Mad cow
disease!!
✔✔Viroids - ✔✔Small plant pathogens that consist of a very short, circular, single-
stranded RNA. They silence genes in the PLANT genome. HDV (hepatitis D virus) is an
example of a human viroid. Although alone HDV is harmless, when coinfected with
hepatitis B, HDV is able to exert its silencing function on human hepatocytes (liver cell).
✔✔Episomes - ✔✔Episomes are a subset of plasmids that are capable of integrating
into the genome of the bacterium
✔✔Positive Sense Viruses - ✔✔Implies that the genome may be directly translated to
functional proteins by the ribosomes of the host cell, just like mRNA.
✔✔Negative Sense Viruses - ✔✔These viruses require synthesis of an RNA strand that
is complementary to the negative sense RNA strand, which can then be used as a
,template for protein synthesis. These viruses must carry an RNA replicase in the virion
to ensure that this synthesis occurs.
✔✔Apoptosis - ✔✔Release of ETC enzymes
✔✔Autolysis - ✔✔Release of lysosome enzymes
✔✔Endosomes - ✔✔transport, package and sort materials to and from membrane. Can
send vesicles to:
1. Cell membrane for recycling
2. Lysosome for degradation
3. Golgi for transport or modification
✔✔Smooth Endoplasmic reticulum - ✔✔Smooth ER lacks ribosomes and is used for
lipid synthesis and detoxification of drugs and poisons. It also transports proteins from
the RER to the Golgi Apparatus.
✔✔HIV life cycle - ✔✔1. Proteins on the envelope bind to CD4 and CR5 on cell surface
2. Virus fuses with cell and empties content into cytoplasm
3. Reverse transcriptase converts RNA to DNA, making errors to generate diversity
4. Integrase inserts virus's DNA into host DNA
5. RNA polymerase converts DNA into RNA, ribosomes make proteins
6. Budding virus particle
7. Mature virus
✔✔Parenchyma - ✔✔Epithelial tissue constitute the parenchyma in most organs,
meaning they are functional parts of the organ (i.e. hepatocytes of the liver, nephron of
the kidneys). They are often polarized, one side faces the lumen, the other interacts
with blood vessels and structural cells.
✔✔Anaphase - ✔✔Centromeres split, each chromatid has its own distinct centromere
chromatids separate-via shortening of the kinetochore fibers.
✔✔Anaphase I - ✔✔Disjunction - each chromosome of paternal origin separates from
its homologue of maternal origin (either chromosome can end up in either daughter
cell).
The separating of the two homologous chromosomes is referred to as segregation.
This explains mendels law of segregation
✔✔Anaphase II - ✔✔Centromeres divide,
sister chromatids pulled to opposite poles.
✔✔Carriers - ✔✔females with a disease-causing X allele that do not exhibit the disease.
,✔✔Cell Cycle - ✔✔A series of specific phases in which the cell grows, synthesizes
DNA, and divides.
✔✔Chromatin - ✔✔less Condensed form of chromosomes during interphase. Makes
DNA available to RNA polymerase for transcription.
✔✔Corona Radiata - ✔✔Lies outside of the zona pellucida. Is a layer of cells that
adhered to the oocyte during ovulation. Meiosis II is triggered when a sperm penetrates
the corona radiata and zona pellucida via acrosomal enzymes.
✔✔Crossing Over - ✔✔homologous chromosomes break at synapsis, (called chiasma)
pieces of DNA are exchanged = recombination of genes.
Genetic diversity!
✔✔Cyclins and Cyclin-Dependent Kinases - ✔✔Molecules responsible for the cell cycle,
via fluctuating levels of cyclin. Cyclins bind CDK to activate them —> activated CDK-
cyclin complex phosphorylates transcription factors.
These then promise transcription of genes required for the next stage of the cell cycle.
✔✔Cytokinesis - ✔✔Separation of the cytoplasm/organelles -> daughter survive on own
✔✔Diploid - ✔✔(2n) contain two copies of each chromosome, 46
✔✔Ejaculation - ✔✔
✔✔roles of NS? - ✔✔When penis is flaccid, norepinephrine from Sympathetic NS is
present.
When sexual stimulation is present, the Parasympathetic NS causes release of NO
which causes Corpora Cavernosa/Spongiosum in penis to fill with blood=erection
Ejaculation meatus=contraction of muscle to expel sperm. The SNS is stimulated and
norepinephrine is released which causes contraction and release of semen into urethra
of penis. Sympathetic NS causes ejaculation, PNS causes erection!!
✔✔Female Sexual Development - ✔✔Ovaries are also under FSH and LH control. They
produce estrogen and progesterone.
Estrogens are secreted in response to FSH
—> the making/maintenance of reproductive system and secondary sex characteristics.
In embryo, they develop the repro. tract. In adults, E initially thickens the uterine lining
(endometrium).
Progesterone is secreted by the corpus luteum (remnant follicle that remains after
ovulation) in response to LH. Involved in development and maintenance of the
endometrium. End of 1st trimester, it's supplied by placenta.
, ✔✔Fertilization - ✔✔Sperm cell penetrates the layers with acrosomal enzymes,
triggering meiosis II. This indicates another meiotic division creating the mature ovum
and another polar body.
✔✔Follicle Stimulating Hormone - ✔✔In males, it triggers sperm maturation via Sertoli
cell stimulation.
In females, FSH causes estrogen to be produced
✔✔Follicular Phase - ✔✔Begins when menstrual flow, shedding of the uterine lining,
begins.
GnRH secretion from the hypothalamus increases in response to decreased estrogen
and progesterone.
Both FSH and LH increase in secretion —> development of follicles occurs
—> follicles produce estrogen, which (negative feedback) causes the decline of GnRH,
FSH, and LH.
Estrogen regrows the ENDOMETRIAL LINING, vascularizing and glandularizing the
decidua (uterine lining forming maternal part of placenta).
✔✔G0 Stage - ✔✔Normal cell/no division offshoot of G1 phase. Cell is simply living and
serving its function.
✔✔G1 Stage - ✔✔Create organelles - energy/protein production
increasing size.
governed by restriction points.
✔✔G1/S Checkpoint - ✔✔DNA good enough for synthesis? p53 protein is the main
control here. Known as the Restriction Point
✔✔If there is damage, cell arrests and p53 fixes problem. - ✔✔
✔✔G2 Stage - ✔✔Cell passes through another quality control checkpoint to ensure
DNA replicated correctly so error isnt passed down through M phase to progeny cells.
✔✔G2/M Checkpoint - ✔✔DNA of adequate size?
organelles replicate to support the daughter cells? (p53 protein plays a role here too.)
✔✔Haploid - ✔✔(n) contain one copy of each chromosome, 23
✔✔Head - ✔✔Covered by acrosome cap derived from Golgi apparatus and is
necessary to penetrate the ovum.
✔✔Hemizygous - ✔✔Only one copy of the X chromosome, ex: males.
