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MT 6315 (Cytogenetics) > UNIT 3 The Cell and Cell Cycle > Flashcards

UNIT 3 The Cell and Cell Cycle Flashcards

1
Q

Which of the following is an antigenic lipid found in the phospholipid bilayer that covers the human cell?

A. Cholesterol
B. Beta-glucan
C. Ergosterol
D. Cardiolipin

A

D. Cardiolipin

Cholesterol, Cardiolipin, Sphingomyelin.

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2
Q

Ankyrin-Spectrin-Band3 of RBCs are an example of which protein in the membrane?

A

Integral Protein

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3
Q

Which is true of ribosomes?

A. The human ribosome is an 80s unit composed of 60s and 20s subunits.
B. The bacterial ribosome is an 80s unit composed of 50s and 30s subunit.
C. The ribosome is composed proteins and tRNA.
D. The ribosomes sizes are measured in sedimentation coefficient units.

A

D. The ribosomes sizes are measured in sedimentation coefficient units. (Svenberg units)

Explanation:
A (False, 40s smaller subunit)
B (False, bacterial ribosome is composed of 70s unit)
C (False, should be rRNA)

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4
Q

The 23s ribosomal subunit is a pan-kingdom marker of which organisms?

A

Prokaryotes

Explanation: Pan-kingdom meaning ALL.

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5
Q

Which of the following organelles is known to sequester calcium and is also known as the sarcoplasmic reticulum in muscles?

A. RER
B. SER
C. Golgi appratus
D. Nuclear envelope

A

B. SER

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6
Q

Which is the site of O-glycosylation of proteins?

A

Golgi apparatus

Explanation: O-glycosylation is a post-translational mechanism.

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7
Q

Which is not true of the mitochondrion?

A. The organelle is more likely to have evolutionarily come from a bigger cell forming a mutualistic relationship with a cyanobacterium inside it.
B. The organelle is involved in oxidative phosphorylation and in programmed cell death.
C. The organelle has its own set of circular DNA distinct from the nucleus that is passed matrilineally.
D. The organelle is implicated in neuromuscular diseases such as MELAS.

A

A. The organelle is more likely to have evolutionarily come from a bigger cell forming a mutualistic relationship with a cyanobacterium inside it.

Explanation: Could be a rickettsial (??) organism, not a cyanobacterium as it is photosynthetic (evolutional origin of chlorophyll, not mitochondria).

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8
Q

True or False

The centrosome is a region composed solely of the cylindrical organelle composed mainly of a protein called tubulin in triplets.

A

False

Incorrect as it would also include the pericentriolar material.

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9
Q

This is made up of a pair of centrioles at its center, and is surrounded by pericentriolar material (PCM) that is important for microtubule nucleation.

A

Centrosome

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10
Q

What are the two function of centrosome?

A

1) Organization of eukaryotic flagella
2) Cilia and the organization of the mitotic and meiotic spindle apparatus that separate the chromosomes during cell division

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11
Q

_____ are a superfamily of related motor-proteins that use a microtubule track in anterograde movement. They are vital to spindle formation during cell division in mitotic and meiotic chromosome separation.

A. Dyneins
B. Kinesin
C. Myosin
D. Actin

A

B. Kinesin

Explanation:
A (Dyneins are retrogade movement)

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12
Q

_____ is a major intracellular degradation system during fasting that derives its degradative abilities from the ____.

A. apoptosis; mitochondrion
B. autophagy; lysosome
C. apoptosis; nucleolus
D. autophagy; peroxisome

A

B. autophagy; lysosome

Explanation: Cell cleaning is autophagy from lysosome.

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13
Q

The pre-rRNA and pre-tRNA are processed in the ____ and exits through ____.

A. nucleolus; the nuclear pore
B. euchromatin; diffusion from the nuclear envelope
C. heterochromatin; the nuclear pore
D. nucleolus; diffusion from the nuclear envelope

A

A. nucleolus; the nuclear pore

It exits through the nuclear pore to go to the cytoplasm to become ribosome and to become amino acid carrier in translation process.

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14
Q

________ are a family of basic proteins that associate with DNA in the nucleus and help condense it into chromatin.

A. scaffold
B. dynein
C. kinesin
D. histone

A

D. histone

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15
Q

Which is true of euchromatin?

A. DNA is tightly packed and light staining
B. Present at inner side of the nucleus
C. Consists 98% of the genome
D. Composed of translatable genes
E. Cannot be acted upon by RNA polymerase

A

B. Present at inner side of the nucleus

Explanation:

A (Chromosomes are LOOSELY packed)
C (Composed 1-2% of the genome)
D (Can be transcribed and translate later on)

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16
Q

True or False

Base pairing between adenine and thymine is facilitated by 3 hydrogen bonds.

A

False

Should be 2 hydrogen bonds.

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17
Q

True or False

Base pairing between cytosine and guanine is facilitated by 2 hydrogen bonds.

A

False

Should be 3 hydrogen bonds.

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18
Q

True or False

Both DNA and RNA consists of long chains of nucleotides held together by ionic phosphodiester bonds.

A

False

Should be COVALENT phosphodiester bonds.

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19
Q

True or False

A nucleotide consist of a sugar molecule attached to a phosphate group on the 5’-carbon and to a nitrogenous base on the 1’-carbon.

A

True

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20
Q

True or False

A nucleotide consist of a sugar molecule attached to a phosphate group on the 1’-carbon and to a nitrogenous base on the 5’-carbon.

A

False

Baliktad.

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21
Q

Which of the following proteins is responsible in releasing the positive supercoils that form during the unwinding of the DNA helix?

A. Helicase
B. SSB proteins
C. DNA gyrase
D. DNA ligase

A

C. DNA gyrase

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22
Q

Which of the following strands can be used as a template for DNA synthesis?

A. 3’-5’ DNA strand
B. 5’-3’ DNA strand
C. Both
D. Neither

A

C. Both

Called semiconservative.

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23
Q

What are the following strands can be used as a template for mRNA synthesis?

A

Antisense strand

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24
Q

A posttranslational processing and modification whereby newly synthesized proteins are combined with a carbohydrate moiety.

A. ubiquitination
B. glycosylation
C. methylation

A

B. glycosylation

Carbohydrate moiety = sugar

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25
Q

It refers to the initial RNA molecules synthesized, with length equivalent to the full length of the DNA transcribed.

A. tRNA
B. pre-MRA/hnRNA
C. snRNA
D. mature mRNA

A

B. pre-MRA/hnRNA

Explanation:
D (have to splice it to become mature)

26
Q

What part is spliced out in order to form the final useable form?

A

Introns

27
Q

Which enzyme is found in the lagging strand but not in the leading strand in replication? How about primase?

A. DNA polymerase
B. Okazaki fragment
C. DNA Ligase

A

C. DNA Ligase

28
Q

In eukaryotic cells, the elongation step of transcription is performed by?

A. DNA polymerase epsilon
B. RNA polymerase II
C. Ribozymes
D. Reverse transcriptase

A

B. RNA polymerase II

29
Q

Which of the following about post-transcriptional modifications is TRUE?

A. 5’ cap protects the DNA from exonucleases
B. The poly-A tail is a long sequence of adenine residues at the 5’ end of mRNA
C. Introns spliced in one case, can be a source of information in another - alternative splicing
D. Includes a process where adding sugars to a hemoglobin molecule creates the glycated form

A

C. Introns spliced in one case, can be a source of information in another - alternative splicing.

Explanation
A (protects the RNA)
B (adenine residue at the 3’ end)
D (adding sugars to a hemoglobin = post-TRANSLATIONAL mechanism)

30
Q

Which of the following stop codons is/are recognized by release factor 1, signaling the termination of translation process?

A. UAA
B. AUG
C. GGA
D. Two of these
E. All of these

A

A. UAA

Stop codons are: UAA and UAG.

31
Q

Which of the following enzymes catalyzes the formation of polypeptide chains?

A. Peptidyl synthetase
B. Peptidyl transferase
C. Aminoacyl synthetase
D. Aminoacyl kinase

A

B. Peptidyl transferase

32
Q

The start codon codes for which amino acid/s?

A

Methionine

33
Q

True or False

There is one tRNA that carries all 20 amino acids and just replaces the amino acid it carries.

A

False

34
Q

Which of the following is also known as RNA-dependent DNA polymerase and is found in viruses like HIV and the tips of telomeric regions of the DNA?

A. RNA pol II
B. DNA pol
C. Peptidyl transferase
D. Reverse transcriptase

A

D. Reverse transcriptase

Creates DNA out of RNA.

35
Q

Which of the following kind of RNAs is involved in gene regulation, for example in silencing some of the genes to avoid expression?

A. snRNA
B. hnRNA
C. siRNA
D. rRNA

A

C. siRNA

36
Q

In the generative cell cycle, the diploid (2N) configuration is seen in all of the following stages, except:

A. G0
B. G1
C. G2
D. None of the above.

A

C. G2

Diploid configuration (2N) is not present anymore when the DNA is replicated. At G2 phase, it is already tetraploid (4N) configuration.

37
Q

During this stage of the generative cell cycle, the cell continues the synthesis of RNA and new proteins. However, at this point, the cell has a tetraploid (4N) configuration.

A. G0
B. G1
C. G2
D. None of the above.

A

C. G2

38
Q

In the generative cell cycle, this is considered to be the temporary resting period. No cell division occurs at this point. Furthermore, the cell has a diploid (2N) configuration at this stage.

A. G0
B. G1
C. G2
D. None of the above.

A

A. G0

39
Q

Which of the following is in a terminal G0 phase?

A. Liver cells
B. Cells of seminiferous tubules post-radiation
C. Cells of myocardium
D. Microglia in the brain

A

C. Cells of myocardium

Explanation:
A & B (All are in a temporary resting phase. Meaning, they can go back to mitosis if there’s necessity for them to go back)
D (Microglia are immune cells, so they can replicate)

40
Q

This is the portion of the chromosome to which proteins that will pull the sister chromatid apart attach:

A. MTOC
B. Kinetochore
C. Kinesin
D. Dynein

A

B. Kinetochore

41
Q

What phase:

Cohesin breakdown

A

Anaphase

So they can pull them to the two sides, cohesin binds together the two sister chromatids.

42
Q

What phase:

Actomyosin ring formation

A

Telophase

Create the cleavage and divide the cell.

43
Q

The cell undergoing mitosis has a tetraploid (4N) chromosomal configuration in all these stages, except:

A. Prophase
B. Metaphase
C. Anaphase
D. Telophase

A

D. Telophase

Explanation: Na-divide into two na in this stage.

44
Q

At what stage of meiotic division does chromosome crossing over occur?

A

Prophase I

Where you see the lazy zebra.

45
Q

Meiosis is necessary to?

A

Generate new DNA sequences in daughter cells.

46
Q

True or nuclear division in meiosis:

A. Bivalent chromosomes -> sister chromatids -> haploid chromosomes
B. 2 sister chromatids -> tetrads -> haploid chromosomes
C. Bivalent chromatids -> DNA replication -> 2N Chromosomes
D. 2N chromosomes -> tetrads -> 4 (2N) chromosomes)

A

A. Bivalent chromosomes -> sister chromatids -> haploid chromosomes

Explanation: Bivalent in Meiosis I -> Sister Chromatids in Meiosis II -> Haploids at the end of Meiosis II

B (2 sister chromatids is also known as tetrads, hindi pwedeng diretso sa haploid chromosomes kasi may Meiosis II pa.)
C (No DNA replication na)
D (Mitosis Stage but 2N chromosomes only)

47
Q

True of cytoplasmic division in human meiosis:

A. Males have four streamlined diploid cells
B. Females have 1 cytoplasmic-ally complete diploid cell
C. Both
D. Neither

A

D. Neither

Haploid ang mga (germ) cells.

48
Q

In the pachytene stage, which of the following creates genetic diversity?

A. Recombinant DNA by transfection
B. Genetic recombination
C. Mutations
D. SRY determination

A

B. Genetic recombination

Explanation: Exchange of information between homologous chromosomes would create genetic diversity.

49
Q

In which stage can be seen the chiasmata formation that causes greater diversity in offspring?

A. Leptotene
B. Diplotene
C. Zygotene
D. Pachytene

A

B. Diplotene

50
Q

In human fetal oogenesis, all developing oocytes develop to this stage and are arrested in prophase I before birth. This suspended state is referred to as the _______ stage. It lasts until meiosis is resumed to prepare the oocyte for ovulation, which happens at puberty or even later.

A

Dichtyotene stage

51
Q

Which of the following is a mitogen?

A. E2F
B. RbP
C. p14
D. p53

A

A. E2F (Eukaryotic transcription factor)

52
Q

Which of the following is a tumor suppressor gene?

A. MYC
B. FGFR
C. p53
D. MAPK

A

C. p53

53
Q

If the ATM gene through the p53 protein still cannot repair massive double-stranded breaks in the DNA, which of the following processes will happen?

A. Bax gene triggers cyclin dependent kinases
B. MYC gene triggers cyclin dependent kinases
C. Bax gene triggers apoptosis
D. MYC gene triggers apoptosis

A

C. Bax gene triggers apoptosis

Explanation: Triggers through intrinsic and extrinsic.

54
Q

Proteins like p14, are examples of:

A

CDK-inhibitors.

Which means they arrest cell division.

55
Q

Which CDK-cyclin and interphase stop is not properly matched?

A. CDK4-Cyclin D-G1/G2
B. CDK2-Cyclin-E-G1/S
C. CDK2-Cyclin A-S/G2
D. CDK1-Cyclin B-G2/M

A

A. CDK4-Cyclin D-G1/G2

Explanation:
CDK4-Cyclin D-G1/S

56
Q

Which of the following is true of the last check point before full on cell division (at the end of metaphase before going to anaphase)?

A. Happens at prophase
B. Securin is bound to separase if aberration occurs
C. Separase is allowed to cut cohesins to destroy bad chromosomes
D. Histones are methylated to change genetic information without changing base sequences

A

B. Securin is bound to separase if aberration occurs

Explanation:
If we don’t want separase to cut the cohesin, then securin will bind separase.

57
Q

Which of the following is true or Barr body production?

A. A product of centromeric action of Xist
B. X inactivation gene products act on the telomere to turn off 1 X gene
C. Barr bodies are present in normal males because the Y chromosome can stand alone
D. In trisomy X, there can be 3 Barr bodies in a squamous epithelium of a female

A

B. X inactivation gene products act on the telomere to turn off 1 X gene

Explanation:
A (Incorrect, should be TELOMERIC action of Xist gene which turns off one X chromosome)
C (No Barr bodies are present in male because hemizygous, they are XY. X chromosomes must exist, cannot turn off in males)
D (Turn off TWO [2] Barr bodies in trisomy X, leave 1 X to turn one or else wala ng dosage ng gene)

58
Q

True or False

The alignment of homologous chromosomes at equatorial plate in meiosis I is non-random so that one gene is always passed from mom to daughter, and another from dad to son.

A

False

Explanation: Gene passed from mom to daughter, could be passed from father to daughter, from mom to son. This is SEGREGATION.

59
Q

X-inactivation, or ______. X-chromosome inactivation in females is a random event. Once the choice for inactivation of either the maternal/paternal X-chromosome is made, it is stably inherited by all daughter cells. Therefore, the females are physiologically mosaic in the expression genes.

A

Somatic Mosaicsm

Explanation: Mosaicsm is when an X-chromosome is turned off in one area, and one of X-chromosome of the pair is turned off in another region. Like in calico cat, which produces their colors. Somatic Mosaicsm can lead to cancer.

60
Q

Paternal age is to ____, as maternal age is to ____.

A. XX mosaicism; Trisomies
B. Aneuploidy; mendelian recessive traits
C. Mendelian dominant traits; aneuploidy

A

C. Mendelian dominant traits; aneuploidy

Explanation
Mendelian dominant traits - de novo sperm cells are produced via Meiosis

Aneuploidy - egg cells that already have had Meiosis I before puberty

61
Q

Which following according to Chargaff counts for the differences in species?

A. Adenine = Thymine
B. Guanine is not = Cytosine
C. A+T is not = C+G
D. A+T = C+G

A

C. A+T is not = C+G

MT 6315 (Cytogenetics) (11 decks)

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