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Molecular Biology > Lecture 1 Cells & Genomes > Flashcards

Lecture 1 Cells & Genomes Flashcards

1
Q

What are the four nitrogenous bases that make up DNA?
A) Adenine, Uracil, Cytosine, Thymine
B) Adenine, Guanine, Cytosine, Thymine
C) Guanine, Uracil, Cytosine, Thymine
D) Adenine, Thymine, Guanine, Uracil

A

B) Adenine, Guanine, Cytosine, Thymine

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2
Q

Which of the following is exclusive to RNA?
A) Adenine
B) Cytosine
C) Uracil
D) Thymine

A

c)Uracil

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3
Q

What is the key structural difference between DNA and RNA?
A) RNA has an extra phosphate group.
B) DNA is single-stranded, and RNA is double-stranded.
C) RNA has a 2’ OH group in the sugar component that makes is more reactive than DNA
D) DNA contains Uracil, while RNA contains Thymine.

A

c)

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4
Q

What type of bonds hold together the backbone of DNA?
A) Hydrogen bonds
B) Ionic bonds
C) Covalent bonds
D) Metallic bonds

A

c) Covalent bonds

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5
Q

In DNA, Adenine pairs with ______, and Guanine pairs with ______.
A) Cytosine; Thymine
B) Thymine; Uracil
C) Uracil; Cytosine
D) Thymine; Cytosine

A

D) Thymine; Cytosine

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6
Q

Which type of gene transfer occurs during sexual reproduction?
A) Vertical gene transfer
B) Horizontal gene transfer
C) Transformation
D) Transduction

A

A) Vertical gene transfer

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7
Q

What is the process by which RNA is synthesized from a DNA template?
A) Translation
B) Replication
C) Transcription
D) Transformation

A

C) Transcription

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8
Q

What is the name of the process in which mRNA is converted into proteins?
A) Transcription
B) Translation
C) Replication
D) Transformation

A

B)Translation

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9
Q

In DNA replication, what type of replication ensures that each new DNA molecule consists of one old strand and one new strand?
A) Conservative replication
B) Dispersive replication
C) Semiconservative replication
D) Nonconservative replication

A

C) Semiconservative replication

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10
Q

Which of the following is a characteristic of eukaryotic cells but not prokaryotic cells?
A) Lack of a nucleus
B) Presence of organelles
C) Smaller cell size
D) High surface area to volume ratio

A

B) Presence of organelles

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11
Q

Why is RNA less stable than DNA?
A) RNA lacks a phosphate group.
B) RNA contains ribose, which has an additional hydroxyl group at the 2’ carbon.
C) RNA is double-stranded, which makes it more reactive.
D) RNA contains Uracil instead of Thymine.

A

B)

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12
Q

Which of the following statements is true regarding the hydrogen bonds in DNA?
A) The A-T base pair has 3 hydrogen bonds, while the G-C base pair has 2 hydrogen bonds.
B) The A-T base pair has 2 hydrogen bonds, while the G-C base pair has 3 hydrogen bonds.
C) Both A-T and G-C base pairs have 3 hydrogen bonds.
D) Hydrogen bonds form between phosphate groups in the DNA backbone.

A

B)

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13
Q

Which of the following statements about DNA replication is correct?
A) DNA strands are replicated in a parallel orientation.
B) DNA replication is unidirectional, occurring only in the 5’ to 3’ direction.
C) DNA replication results in two identical molecules, each with one old and one new strand.
D) Replication can only occur in prokaryotic cells due to the simpler genome structure.

A

C)

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14
Q

What factor primarily determines the melting temperature (Tm) of DNA?
A) The length of the DNA strand
B) The ratio of purines to pyrimidines
C) The G-C content, as G-C pairs have more hydrogen bonds
D) The presence of thymine dimers in the strand

A

c) The G-C content due to more hydrogen bonds being present

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15
Q

Why is yeast often used as a model organism in molecular biology?
A) Yeast has a large and complex genome that mimics human genetics.
B) Yeast is multicellular and demonstrates high cellular variability.
C) Yeast has a small genome, short generation time, and is easy to genetically manipulate.
D) Yeast cells lack a nucleus, making them simpler to study.

A

c) small genome, short generation time, easy to modify/manipulate

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16
Q

During transcription, what determines the sequence of the RNA molecule?
A) The amino acid sequence of a protein
B) The complementary sequence of the DNA template strand
C) The anticodon sequence on tRNA molecules
D) The number of ribosomes attached to the mRNA

A

B) the complimentary sequence of the DNA template strand

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17
Q

Which statement about Hox genes and body patterning is correct?
A) Hox genes are involved in transcriptional regulation, determining cellular metabolism.
B) The position of Hox genes on the chromosome directly corresponds to the body part they control.
C) Hox genes regulate the replication of DNA in multicellular organisms.
D) Mutations in Hox genes do not affect body development.

A

b) The position of Hox henes on the chromosome directly corresponds to the body part they control

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18
Q

What is the primary role of histone modification, such as acetylation and methylation, in gene expression?
A) To compact DNA and make it inaccessible to transcription factors.
B) To unwind DNA, allowing transcription factors to access specific genes.
C) To repair mutations in the DNA sequence.
D) To promote the synthesis of mRNA at the ribosome.

A

b) To unwind DNA

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19
Q

In the process of gene expression regulation, what effect does histone acetylation generally have on chromatin?
A) It tightens chromatin structure, reducing gene expression.
B) It loosens chromatin structure, increasing gene expression.
C) It prevents RNA splicing by removing exons.
D) It inhibits the binding of transcription factors to the promoter region.

A

B) Acetylation lossens chromatin structure, increasing gene expression

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20
Q

What functional group is attached to the 5’ end of a DNA strand?
A) Hydroxyl group (-OH)
B) Phosphate group (-PO₄³⁻)
C) Methyl group (-CH₃)
D) Amine group (-NH₂)

A

b) Phosphate group (-PO4)

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21
Q

What is attached to the 3’ end of a DNA strand, allowing elongation during DNA replication?
A) A phosphate group (-PO₄³⁻)
B) A hydroxyl group (-OH)
C) A nitrogenous base
D) A ribose sugar

A

b) Hydroxyl group

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22
Q

In the DNA double helix, which direction do the two strands run relative to one another?
A) Parallel, both 5’ to 3’
B) Parallel, both 3’ to 5’
C) Antiparallel, one strand 5’ to 3’ and the other 3’ to 5’
D) Circular, with no distinct ends

A

c) Antiparallel

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23
Q

Phosphodiester bonds in DNA form between which two components?
A) The phosphate group of one nucleotide and the nitrogenous base of another
B) The phosphate group of one nucleotide and the 3’ hydroxyl group of the adjacent nucleotide
C) The nitrogenous bases of two nucleotides
D) The sugar of one nucleotide and the nitrogenous base of the adjacent nucleotide

A

b) The phosphate group of one nucleotide and the 3’ hydroxyl group of the adjacent nucleotide

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24
Q

During DNA replication, DNA polymerase adds nucleotides to which end of the growing DNA strand?
A) 3’ end
B) 5’ end
C) Both 5’ and 3’ ends simultaneously
D) Neither, DNA polymerase synthesizes in the middle of the strand

A

A) 3’ end

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25
Q

Which bond is responsible for linking adjacent nucleotides in a single DNA strand?
A) Hydrogen bond
B) Phosphodiester bond
C) Peptide bond
D) Glycosidic bond

A

b)

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26
Q

What type of bond holds together the nitrogenous bases in the center of a DNA double helix?
A) Covalent bond
B) Phosphodiester bond
C) Ionic bond
D) Hydrogen bond

A

d) Hydrogen bonds

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27
Q

In a DNA strand, the 3’ carbon of the sugar is attached to which component?
A) A nitrogenous base
B) A phosphate group
C) Another sugar’s 5’ phosphate group
D) A hydrogen bond

A

c)

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28
Q

Which of the following statements about antiparallel DNA strands is true?
A) Both strands are oriented 5’ to 5’.
B) One strand runs 5’ to 3’, while the other runs 3’ to 5’.
C) Both strands run 3’ to 3’.
D) The directionality is irrelevant for DNA replication.

A

b)

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29
Q

What is the enzyme responsible for copying a DNA sequence into a complementary RNA sequence during transcription?
A) DNA polymerase
B) RNA polymerase
C) Ribosome
D) Ligase

A

b) RNA polymerase

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30
Q

n transcription, the template for RNA synthesis is:
A) An RNA strand
B) A DNA strand
C) A protein
D) A ribosome

A

b) DNA strand

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31
Q

Which of the following best describes the product of transcription?
A) A newly synthesized DNA strand
B) An mRNA molecule
C) A ribosomal protein
D) A polypeptide chain

A

b)

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32
Q

What occurs during the process of translation?
A) DNA is copied into RNA.
B) RNA is synthesized from DNA.
C) mRNA is used to synthesize a protein.
D) RNA is spliced to remove introns.

A

c)

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33
Q

Which molecule carries the genetic instructions for assembling proteins during translation?
A) DNA
B) tRNA
C) mRNA
D) rRNA

A

c)mRNA

34
Q

Which process converts the information stored in mRNA into a sequence of amino acids to form a protein?
A) Transcription
B) Translation
C) Replication
D) Splicing

A

b) Translation

35
Q

Which of the following is an example of horizontal gene transfer?
A) A bacterium receiving a gene from another bacterium through a plasmid
B) A child inheriting genes from their parents
C) The transfer of genes between two cells during mitosis
D) The transfer of genes from parents to offspring in reproduction

A

A) a bacteria transferring a gene from to another bacterium

36
Q

Vertical gene transfer occurs during which process?
A) Sexual reproduction
B) Asexual reproduction in bacteria
C) Conjugation in bacteria
D) Cloning in a laboratory

A

a) Sexual reproduction

37
Q

Which of the following best describes translation?
A) DNA is copied into RNA.
B) RNA is synthesized into DNA.
C) mRNA is decoded to produce a specific sequence of amino acids.
D) Proteins are converted into nucleotides.

A

c)

38
Q

Horizontal gene transfer often occurs in __________, allowing them to exchange genetic material with one another outside of reproduction.

fill in the blank

A

bacteria

39
Q

During translation, transfer RNA (tRNA) molecules deliver __________ to the ribosome, where they are assembled into proteins.

fill in the blank

A

amino acids

40
Q
A
41
Q

What are mutations?

A

permanent change in the DNA sequence that make up a gene

42
Q

Which of the following is a characteristic of prokaryotic cells?
A) They have a nucleus.
B) They contain membrane-bound organelles.
C) They are smaller and more variable in shape.
D) They perform transcription inside the nucleus.

A

c)

43
Q

Where does transcription occur in eukaryotic cells?
A) Cytoplasm
B) Ribosomes
C) Nucleus
D) Mitochondria

A

c) Nucleus

44
Q

Which of the following is true about eukaryotic cells compared to prokaryotic cells?
A) Eukaryotic cells are smaller and less complex.
B) Eukaryotic cells do not contain membrane-bound organelles.
C) Eukaryotic cells are larger, more complex, but less flexible.
D) Eukaryotic cells have a higher surface-to-volume ratio.

A

c)

45
Q

Where does translation occur in both prokaryotic and eukaryotic cells?
A) Nucleus
B) Cytoplasm
C) Endoplasmic reticulum
D) Mitochondria

A

B) Cytoplasm

46
Q

Which of the following features is found only in eukaryotic cells?
A) Ribosomes
B) Cell membrane
C) Nucleus
D) DNA

A

c) Nucleus

47
Q

In prokaryotic cells, transcription occurs in the __________, while in eukaryotic cells, it occurs in the __________.

fill in the blank

A

Answer: cytoplasm; nucleus

48
Q

Which of the following is NOT a key reason for using model organisms in research?

A) Genetic similarity to humans or other species
B) Long lifespan and slow reproduction
C) Ease of genetic manipulation
D) Short life cycles and rapid reproduction

A

b)

49
Q

Why is yeast considered a simple model organism for studying eukaryotes?
A) It has a complex genome
B) It is a multicellular organism
C) It has a small genome size and is easy to culture
D) It cannot be stored in the freezer

A

c)

50
Q

What is a significant advantage of using armadillos in research?
A) They can survive in harsh conditions
B) They produce identical offspring, eliminating many variables
C) They have a long generation time
D) They are easy to genetically modify

A

b)

51
Q

What concept does the position of Hox genes on a chromosome relate to?
A) Genetic similarity
B) Collinearity in body part regulation
C) Semiconservative replication
D) Genome size

A

B) Collinearity - the position of hox genes on a chromosome correspond to which body part it regulates

52
Q

What is one of the key reasons mice are used as model organisms in mammalian studies?
A) They have a long lifespan
B) They are difficult to breed
C) There is strong homology between humans and mice
D) They produce non-identical offspring

A

c) strong homology

53
Q

Explain how the R strain of Streptococcus pneumoniae can become pathogenic when exposed to the S strain. What role does DNA play in this transformation?

SA

A

The R strain of Streptococcus pneumoniae is non-pathogenic and does not cause pneumonia. However, when it is exposed to heat-killed S strain cells or cell-free extracts from the S strain, a process called transformation occurs. This exposure allows the R strain to take up heritable information from the S strain, specifically DNA. The DNA from the S strain carries the genetic instructions for pathogenicity. As a result, the R strain transforms into the S strain, and the daughter cells become pathogenic, capable of causing pneumonia. This discovery was pivotal in demonstrating that DNA is the molecule responsible for carrying heritable information.

54
Q

What are introns?
A) The coding regions of a gene that are translated into proteins
B) The non-coding sequences within a gene that are removed during RNA splicing
C) The sections of DNA that initiate transcription
D) The portions of mRNA that are translated into amino acids

A

B)

55
Q

What are exons?
A) The regions of DNA that are never transcribed
B) The sequences in a gene that remain in the mature RNA molecule
C) The parts of the protein that are not functional
D) The intronic sequences that are mistakenly included in mRNA

A

b)

56
Q

In which phase of the cell cycle is DNA the least condensed?

a) Prophase
b) Metaphase
c) Interphase
d) Anaphase

A

c) Interphase

57
Q

What is the primary function of euchromatin in a non-dividing cell?

a) To ensure DNA is tightly packed
b) To facilitate active transcription of genes
c) To prevent DNA damage during cell division
d) To form the mitotic spindle

A

b)

58
Q

Which of the following best describes the structural organization of DNA during metaphase?

a) DNA is loosely packed and easily accessible for transcription.
b) DNA is tightly condensed into visible chromosomes.
c) DNA is replicated and spread throughout the nucleus.
d) DNA is uncoiled and interacts with RNA polymerases.

A

b)

59
Q

Histones play a critical role in:

a) DNA replication
b) Compaction of DNA into nucleosomes
c) Formation of centromeres
d) Separation of sister chromatids

A

b) Compaction of DNA into nucleosomes

60
Q

Heterochromatin is generally associated with:

a) Actively transcribed genes
b) Highly condensed and transcriptionally inactive DNA
c) The centromeres of dividing cells
d) The unwinding of DNA during replication

A

b)

61
Q

Which of the following statements best describes heterochromatin?

a) It is transcriptionally active and loosely packed.
b) It is transcriptionally inactive and highly condensed.
c) It contains genes that are frequently expressed.
d) It replicates early during the S-phase

A

b)

62
Q

Which of the following is a function of heterochromatin?

a) Gene activation
b) Maintaining chromosome structure and gene silencing
c) Early replication during the S-phase
d) Increasing gene expression

A

b)

63
Q

Which chromatin type is most likely to contain genes that are frequently transcribed?

a) Heterochromatin
b) Euchromatin
c) Facultative heterochromatin
d) Constitutive heterochromatin

A

b) Euchromatin

64
Q

What is the position effect in heterochromatin?

a) The movement of chromosomes during mitosis
b) The spreading of heterochromatin into neighboring euchromatic regions, silencing genes
c) The increase in gene expression due to a gene’s location in euchromatin
d) The effect of gene mutations on chromosome structure

A

B)

65
Q

What causes a gene to be silenced by the position effect?

a) Mutation in the gene sequence
b) The gene moving to a euchromatic region
c) The gene being located near or within heterochromatin
d) Insertion of new sequences into the gene

A

c)

66
Q

Which of the following examples best illustrates the position effect variegation?

a) A gene mutates and stops functioning
b) A gene is relocated to a heterochromatic region, leading to mosaic expression patterns
c) A gene is deleted from the chromosome
d) A gene is amplified, leading to higher levels of expression

A

b)

67
Q

How is the silencing effect in PEV passed on to daughter cells?

a) Through mutations in the DNA sequence
b) By inheritance of epigenetic marks that maintain the heterochromatin state
c) By duplicating the heterochromatin gene
d) By deleting inactive genes during cell division

A

b)

68
Q

In Drosophila, variegated eye color due to PEV is a result of:

a) Mutations in the white gene
b) Spreading of heterochromatin that silences the white gene in some cells
c) Overexpression of the white gene
d) Duplication of the white gen

A

b)

69
Q

In Drosophila melanogaster (fruit flies), how does the relocation of the white gene near heterochromatin result in variegated eye color, and what does this illustrate about heritable position effect variegation (PEV)?

SA

A

The white gene in Drosophila is responsible for producing a pigment that gives the flies their characteristic red eye color. When the white gene is relocated near a region of heterochromatin due to chromosomal rearrangement, the proximity to the heterochromatin can lead to the spreading of heterochromatin into the region containing the white gene. As a result, some cells express the white gene normally and produce red pigment, while other cells have the gene silenced and do not produce pigment, leading to variegated eye color (patches of red and white).

This phenomenon illustrates heritable position effect variegation (PEV) because the silencing of the white gene can be passed down through subsequent cell divisions. The epigenetic marks associated with heterochromatin are inherited, allowing the pattern of gene expression (or silencing) to persist in daughter cells. The result is a mosaic appearance in the eye color of the flies, demonstrating how the chromosomal context and position can influence gene expression without altering the DNA sequence itself.

70
Q

What is the primary reason for the mosaic black and orange coloration in calico cats?

a) Genetic mutation in the fur color gene
b) Random X chromosome inactivation in heterozygous female cats
c) Dominant inheritance of the black color gene
d) Influence of environmental factors on fur color

A

b)

71
Q

Explain how X chromosome inactivation in heterozygous female calico cats leads to their characteristic black and orange fur coloration, and describe the origin of the white patches in their coat.

SA

A

In calico cats, the mosaic black and orange fur coloration results from X chromosome inactivation in heterozygous females that possess one X chromosome with a black fur allele (B) and another with an orange fur allele (b). During early embryonic development, one of the X chromosomes in each cell is randomly inactivated. Cells that inactivate the X chromosome carrying the black allele express the orange fur color, while those that inactivate the X chromosome with the orange allele express black fur. This creates a patchwork of black and orange fur across the cat’s body.

The white patches in calico cats arise from the expression of an autosomal gene responsible for white fur coloration, which can mask the black and orange fur color genes. The interaction between this autosomal gene and the X-linked color genes contributes to the overall unique appearance of calico cats.

72
Q

What is the primary effect of histone acetylation on chromatin structure?

a) Increases DNA methylation
b) Decreases DNA accessibility
c) Promotes a more open chromatin structure
d) Causes histone degradation

A

c) Promotes a more open chromatin structure - it will loosen your chromatin structure

73
Q

Which enzyme is responsible for adding acetyl groups to histones?

a) Histone methyltransferase
b) Histone deacetylase
c) Histone acetyltransferase
d) Histone kinase

A

c) Histone acetyltransferase or HATs

74
Q

What role does histone deacetylase (HDAC) play in gene regulation?

a) Adds acetyl groups to histones, promoting gene activation
b) Removes acetyl groups from histones, leading to gene repression
c) Adds methyl groups to histones, silencing genes
d) Inhibits the binding of transcription factors

A

b)

75
Q

What is it called when an existing gene is modified at random by changes in the DNA sequence that occur via DNA replication and repair

A

Intragenic mutation

76
Q

An existing gene is duplicated by accident

A

gene duplication

77
Q

What is it called when 2 or more existing genes break and rejoin to make a hybrid gene that have DNA segments originally belonging to 2 seperate genes

A

DNA Segment shuffling

78
Q

Which of the following model organisms contain about 6600 protein coding genes:
a) Yeast
b) Mice
c) Zebra fish
d) E. Coli
e) C. Elegans (roundworm)

A

a) Yeast

79
Q

Which model organism has been used countless times to study classical genetics and is based on the learning of genetics?
a) Drosophilia melangaster
b) E. Coli
c) S. cervisiaie
d) Arabiodopsis thaliana

A

a)

80
Q
A

Molecular Biology (9 decks)

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