Unit 3: Cell Cycle Flashcards by JULIA CASSANDRA RECCION

Represents a self-regulated sequence of events that controls cell growth and cell division

Cell cycle

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goal of cell cycle

produce 2 daughter cells, each containing chromosomes identical to those of the parental cell

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2 principal phases of cell cycle

interphase & m phase (mitosis)

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phospholipid bilayer; hydrophobic head & hydrophobic tail in 2 layers

cell membrane

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what does the cell membrane contain?

cholesterol
cardiolipin
shingomyelin
oligosaccharides
membrane proteins

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integral proteins

membrane proteins

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lipid-anchored proteins & peripheral proteins

membrane proteins

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several organelles are found in?

cytoplasm

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organelles are suspended in a fluid-filled region called?

cytosol

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T/F: The presence and abundance of the different organelles varies between different tissues and different organisms

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Non-membrane bound organelles that are responsible for the synthesis of protein

ribosome

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building block of a protein

amino acid

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sequence of a ribosome

mRNA → transcription → reading of codons (translation) → synthesis of a specific protein mRNA

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ribosome is made up of?

small subunit (40S) & large subunit (60S)

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contains protein and rRNA which are synthesized
in the nucleolus

rubosome

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where can ribosomes attach?

rough ER
cytoplasm (free floating)
perinuclear membrane

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Double membrane-bound organelle

endoplasmic reticulum

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Appear as folded layers that seems to be connected to the nuclear membrane

endoplasmic reticulum

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responsible for protein synthesis because of the ribosomes embedded in this membrane

rough ER

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double membrane folded in layers is called in such a way because of the absence of the ribosome in its membrane

smooth ER

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responsible for glucose and lipid synthesis

smooth ER

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network of smooth membranes consisting of flattened, disc-like cisternae with dilated rims and associated vesicles and tubules

golgi body

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Where the newly synthesized protein is processed and modified

golgi body

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Sorts and packs the proteins / products produced by the cell

golgi body

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T/F: golgi body encloses the products and produces vesicles containing proteins which travel to the extracellular environment via endocytosis

F; exocytosis

Provides energy to the cell by producing ATPs in a process called cellular respiration

mitochondrion

Contains several enzymes and proteins embedded in its inner membrane called cristae

mitochondrion

● A type of plastid which is found in plant cell ● Contains chlorophyll located at the thylakoid membrane ● The thylakoids are stacked together to form granum (plural grana) suspended in stroma ● Responsible for the process called photosynthesis

chloroplasts

complex structure that contains two barrel shaped centrioles surrounded by amorphous, electron dense pericentriolar material PCM

centrosome

A single membrane-bound organelle In animal cells, vacuoles are generally small and help sequester waste products In plant cell, this is a fluid filled structure that is made up mostly of water

vacuole

An elaborate interactive network composed of three well defined filamentous structures ○ Microtubules ○ Microfilaments ○ Intermediate filaments

cytoskeleton

Provide structural support and internal framework responsible for positioning various organelles within the interior of the cell Provides movement of materials and organelles in cell

cytoskeleton

Found in the interior of the cell where they maintain cell shape by resisting compressive forces

microtubules

Thicken the cortex around the inner edge of a cell; they resist tension

microfilaments

Found throughout the cell and hold organelles in place

intermediate filaments

● Also known as microbodies ● Membrane bound, multifunctional organelles that carry out a diverse metabolic reactions including substrate oxidation leading to formation of hydrogen peroxide

peroxisomes

● The command center of the cell because it commands the cellular activity of the entire cell ● Made up of: - Nuclear membrane - Chromosomes - Nucleolus

nucleus

● Each of these membranes contains two layers of phospholipids, arranged with their tails pointing inward (forming a phospholipid bilayer) ● It contains nuclear pores for easy transport of materials such as mRNA to the cytoplasm

nuclear membrane

● Threadlike strands of nuclear DNA with proteins called histones ● These are carrier of genetic materials that occur by pairs (with homologous chromosomes)

chromosome

T/F: In meiosis, the chromosomes condensed from chromatin to meta-chromosome becoming more visible under the light microscope

● Found inside the nucleus suspended in nucleoplasm ● Is an irregular-shaped nuclear structures that function as ribosome-producing organelle

nucleolus

nucleolus is more prominent during what stage?

interphase

● A rigid structure found in plants ● This provides support and protection for the cell it surrounds

cell wall

cell wall contains

pectin glycan cellulose microfibrils Expands from primary cell wall to middle lamella

Monitor and modulate the progression of cells in response to intracellular or environmental signals

checkpoints

Internal quality control mechanisms represented by biochemical pathways that control transition between cell cycle stages

checkpoints

checkpoints are introduced by?

Leland Hartwell and Ted Weinert (1988)

Defined as the failure to arrest the cell cycle before or at mitosis, resulting in aberrant chromosome segregation

mitotic catastrophe

Caused by malfunction of cell cycle checkpoints and may lead to cell death and tumor cell development

mitotic catastrophe

T/F: in mitotic catastrophe, malignant cells lose contact inhibition

a normal process where a cell inhibits cellular division once in contact with a cell

contact inhibition

The Cell Cycle Is Regulated by?

protein kinases

The key enzymes that control the transitions between the different states of the cell cycle, and the entry of nondividing cells into the cell cycle, are the?

cyclin-dependent protein kinases, or CDKs

T/F: Endogenous hormones such as auxin, cytokinins, abscisic acid, gibberellins and brassinosteroids as well as environmental factors all regulate progression through the cell cycle

T/F: Cell cycle events take place with clock-like precision

A group of highly conserved serine/threonine kinases

cyclin-dependent kinases(CDKs)

are among the most important core cell cycle regulators

cyclins

help to promote passage through “ Start” or the restriction point in late G1

G1-cyclins

bind Cdks at the end of G1 and commit the cell to DNA replication

G1/S-cyclins

binds Cdks during S phase and are required for the initiation of DNA replication

S-cyclins

promote the events of mitosis

M cyclins

are enzymes that phosphorylate proteins using ATP

protein kinases

T/F: The regulated activity of CDKs is essential for the transitions from G1 to S and from G2 to M, and for the entry of dividing cells into the cell cycle.

F; nondividing

2 tyrosine phosphorylation sites of cdks

one causes activation and one causes inactivation

T/F: The transition from G1 to S requires a set of cyclins ( G1 cyclins) different from those required in the transition from G2 to mitosis, where mitotic cyclins activate the CDKs

T/F: Specific kinases carry out both the stimulatory and the inhibitory phosphorylation

can remove phosphate from CDKs, either stimulating or inhibiting their activity, depending on the position of the phosphate

protein phosphatases

2 CDK important mechanisms

1. cyclin synthesis & destruction 2. phosphorylation & dephospho of key amino acid residues w/in the CDK protein

T/F: CDKs are inactive unless they are associated with a cyclin

are synthesized and then actively degraded (using ATP) at specific points in the cell cycle

cyclins

Cyclins are degraded in the ______ by a large proteolytic complex called the ________.

cytosol, proteasome

T/F: Before being degraded by the proteasome, the cyclins are marked for destruction by the attachment of a small protein called ubiquitin, a process that requires ATP

It is when the cell prepares itself for cellular division

interphase

Usually the longest and the most variable phase of the cell cycle, and it begins at the end of M phase

G1 phase

The cell gathers nutrients and synthesizes RNA and proteins necessary for DNA synthesis and chromosome replication

G1 phase

G1 phase hrs

9-12

damage checkpoint monitors the integrity of newly replicated DNA

G1 DNA

○ Sensitive to the size of the cell, the state of the cell’s physiologic processes, and its interactions with extracellular matrix ○ Mediated by interactions between pRb and a family of E2F with target promoters ○ In normal cells, proper interaction between pRb and E2F turns off many genes and blocks cell-cycle progression

Restriction checkpoint

● DNA is replicated ● Chromosome replication is initiated at many different sites along the chromosomal DNA → replicon ● Checkpoint: S DNA-damage checkpoint

S phase

S phase hrs

7.5 to 10 hrs

Unit 3: Cell Cycle Flashcards

(80 cards)