Deck 4: Cellular Aging

Question 1

True or false: On the existing DNA strand,DNA polymerase moves in the 5′→ 3′ direction.

Answer 1

False

Question 2

Eukaryotic cells duplicate and divide through an orderly sequence of events defined as:
(a)molecular biology.
(b)cell replication.
(c)the cell cycle.
(d)cell biology.

Answer 2

C

Question 3

The replication machinery moves backward on the lagging strand,creating small segments called:
(a)DNA fragments.
(b)lagging fragments.
(c)cohesins.
(d)Okazaki fragments.

Answer 3

D

Question 4

G₁,S,and G₂ are collectively known as the M phase.

Question 5

phase in which cell separation occurs during cell division is called:
(a)M phase.
(b)prometaphase.
(c)cytokinesis.
(d)telophase.

Question 6

The ______ family of enzymes participates in reactions that mark improperly folded proteins for destruction and may have a significant role in the development of Alzheimer's and Parkinson's diseases.
(a)ubiquitin ligase
(b)DNA polymerase
(c)helicase
(d)primase

Question 7

separation of the double helix to allow new DNA synthesis is divided into thousands of individual reactions starting at sites along the DNA called:
(a)replication beginnings.
(b)dividing sites.
(c)separation origins.
(d)replication origins.

Question 8

True or false: DNA replication is initiated by the expression of nuclear proteins known as S-cyclins.

Question 9

Fill in the blank: Initiation of the cell cycle in multicellular organisms appears to occur only when the cell receives an extracellular signal from substances called ______.

Question 10

synthesis occurs in which phase?
(a)S
(b)M
(c)G₁
(d)G₂

Question 11

The helicase and primase make up a protein replication complex called:
(a)DNA polymerase.
(b)the primosome.
(c)DNA replicase.
(d)DNA ligase.

Question 12

Fill in the blanks: DNA replication moves in both directions from the replication origins,creating the ______ and ______ strands.

Question 13

Separation of the sister chromatids occurs in ______.

Question 14

of the life of a normal cell is spent in which phase?
(a)G₁ phase (gap 1)
(b)S phase
(c)G₂ phase (gap 2)
(d)M phase

Question 15

True or false: The promoter region of a gene can be located thousands of nucleotides away from the coding region of the gene.

Question 16

If a cell does not receive a mitogenic signal at the correct time,it dismantles the cell cycle control mechanisms and enters:
(a)S phase.
(b)G₀ phase.
(c)G₁ phase.
(d)M phase.
Replicative Senescence

Question 17

Cells that enter G₀ are metabolically active but reproductively silent.

Question 18

contractile ring composed of ______ and ______ forms at the center of the furrow that begins the separation of the two newly formed cells.
(a)connectins;condensin
(b)actin;myosin
(c)centromeres;actin
(d)myosin;connectins

Question 19

Pauses in DNA replication that result from checkpoint regulation are often referred to as:
(a)genetic brakes.
(b)checkpoint recesses.
(c)molecular brakes.
(d)S-cyclin controls.

Question 20

During prophase,the ______ duplicate and move to opposite sides of the nuclear envelope.
(a)spindles
(b)condensins
(c)chromatids
(d)centrosomes
Regulation of the Cell Cycle

Question 21

True or false: Maintaining the proper structure of a molecule is generally known as molecular fidelity.

Question 22

True or false: Because the proteins that help to maintain molecular fidelity are also subject to the second law of thermodynamics,the ability to repair or replace damaged biomolecules also decreases with age.

Question 23

True or false: It is generally accepted that replicative senescence provides a good model for aging of the whole organism.

Question 24

Oxygen-based metabolism is referred to as ______,and metabolism without oxygen as ______.
(a)aerobic;anaerobic
(b)anaerobic;anaerobic
(c)aerobic;anabolic
(d)anaerobic;aerobic

Question 25

One exciting new area of research where the concept of replicative senescence has the potential for offering significant value is the interface between:
(a)aging and disease.
(b)cell functioning and disease.
(c)morphological alterations and DNA replication.
(d)replicative senescence and longevity.

Question 26

In total numbers,the majority of human cells are:
(a)fully mitotic.
(b)semi-mitotic.
(c)rapidly mitotic.
(d)non-mitotic.
The Cause of Cellular Aging: Accumulation of Damaged Biomolecules

Question 27

The ______ law of thermodynamics describes how the transfer of energy from one form to another is not 100% efficient and some of the energy becomes unusable.
(a)first
(b)second
(c)third
(d)fourth

Question 28

True or false: Cell lines are immortal cell cultures.

Question 29

Short-answer question: Briefly describe the three phases of a cell culture.

Question 30

Fill in the blank: When unusable energy leaves the system,the system becomes randomly rearranged,moving from more order to less order.It is this movement toward increasing ______ that is associated with the accumulation of damaged proteins,leading to aging.

Question 31

True or false: The cellular accumulation of damaged biomolecules decreases after sexual maturation.

Question 32

Because the aging of an organism reflects a gradual decline in function after the reproductive period,the decline and eventual loss of cell division has generally been viewed as characterizing cellular aging;this period is known as:
(a)cell replication.
(b)cell arrest.
(c)replicative senescence.
(d)cell mortality.

Question 33

The loss of molecular fidelity most closely supports which theory of aging?
(a)antagonistic pleiotropy
(b)disposable soma
(c)mutation accumulation
(d)genetic drift
Oxidative Stress and Cellular Aging

Question 34

True or false: Mitotic somatic cells taken from aged individuals can often show robust population doubling rates.

Question 35

The ______ law of thermodynamics applies to the conversion of energy from one form to another;energy is neither created nor destroyed.
(a)first
(b)second
(c)third
(d)fourth

Question 36

Senescent cells typically display all of the following characteristics except:
(a)cellular enlargement.
(b)decrease in the size of the nucleus and multinucleated cells.
(c)increase in the distance between cells.
(d)decrease in viable extracellular matrix proteins.

Question 37

Which mechanism is considered the primary cause in the accumulation of damaged cellular proteins?
(a)oxidative stress
(b)glycosylation
(c)formation of insoluble protein aggregates
(d)none of the above

Question 38

Fill in the blank: The maximum number of population doublings in a cell culture is known as the ______ limit.

Question 39

True or false: Human embryonic cells maintained in culture are immortal.

Question 40

The total energy of a biological process is called ______ (H)and equals usable energy (______,G)plus unusable energy (______,S).
(a)free energy;entropy;enthalpy
(b)entropy;free energy;enthalpy
(c)free energy;enthalpy;entropy
(d)enthalpy;free energy;entropy

Question 41

Fill in the blank: ______ is the final acceptor of electrons in the electron transfer system.

Question 42

Of the cell structures listed below,which,in general,is/are the most vulnerable to damage by oxygen-centered radicals?
(a)Golgi complex
(b)nucleus
(c)ribosomes
(d)lipid membranes

Question 43

Together,the end products of the TCA cycle and electron transfer system are:
(a)carbon dioxide and water.
(b)carbon monoxide and water.
(c)electrons and oxygen.
(d)oxygen and carbon dioxide.

Question 44

Which two vitamins help to prevent the formation of lipid peroxides?
(a)E and D
(b)C and E
(c)C and A
(d)E and A

Question 45

What structures shorten with each replication cycle?
(a)Okazaki fragments
(b)telomeres
(c)replication origins
(d)replication forks

Question 46

True or false: The telomere sequence is highly conserved across the eukaryotic kingdoms.

Question 47

In general,telomerase is expressed only in the ______ and ______ cells.
(a)germ;stem
(b)stem;somatic
(c)somatic;germ
(d)sperm;somatic

Question 48

The mitochondria of aerobic organisms use 95% of all oxygen consumed by the body in the synthesis of:
(a)DNA.
(b)proteins.
(c)adenosine triphosphate (ATP).
(d)carbohydrates.

Question 49

True or false: The mitotic cell will enter the G₀ phase if there is no end cap on the telomeres.

Question 50

The enzyme responsible for maintaining telomere length is:

A)DNA polymerase.
B)RNA polymerase.
C)telomerase.
D)telomere synthetase.

Question 51

True or false: Oxidized compounds have fewer electrons than reduced compounds,making them less reactive.

Question 52

Fill in the blank: The possible lack of sufficient DNA to initiate the final RNA primer on the lagging strand template is generally referred to as the ______.

Question 53

High ATP-ADP ratios in the mitochondrial matrix ______ the TCA cycle,and thus electrons are not shuttled to the ETS.
(a)inhibit
(b)activate
(c)initiate
(d)reverse

Question 54

True or false: Oxygen-centered radicals can be used to benefit the organism.
Telomere Shortening and Replicative Senescence

Question 55

Without the ______ on the end of the telomeres,DNA polymerase reads the ends of the telomeres as strand breaks and initiates the DNA repair mechanism.
(a)telomerase
(b)repetitive G and T bases
(c)primase
(d)end cap

Question 56

True or false: The telomere-shortening theory is an example of a stochastic theory of cell aging.

Question 57

True or false: Although the mitochondria generate the majority of oxygen-centered radicals,most associated damage occurs in the cytoplasm.