PHYSIO EXAM 1

In the hierarchy of biological organization, what level do multiple tissues aggregate to form?

Organs

The cell membrane's structure is primarily described as a _____ bilayer.

phospholipid

In the cell membrane's phospholipid bilayer, which part of the molecule is in direct contact with the intracellular and extracellular water?

Hydrophilic heads

Which specific type of membrane protein is synonymous with 'intrinsic' membrane proteins?

Integral proteins

What is the function of Cell Adhesion Molecules (CAMs) within the cell membrane?

They anchor cells to their neighboring cells.

How do carrier proteins transport substances across the cell membrane?

They move substances down electrochemical gradients via facilitated diffusion.

Which membrane components are responsible for actively transporting ions against their concentration gradients?

Pumps

Mitochondria produce ATP through the specific process of _____.

oxidative phosphorylation

Besides energy production, what critical role do mitochondria play in cell life-cycle management?

They play a role in apoptosis (programmed cell death).

Explain the inheritance pattern of mitochondrial DNA.

Mitochondrial inheritance is exclusively maternal.

Lysosomes utilize _____ to digest endocytosed bacteria and worn-out cellular components.

enzymes

What clinical condition occurs when a lysosomal enzyme is congenitally absent, causing material accumulation?

Lysosomal storage disease

Which organelle is characterized by enzymes that either produce or break down $H_{2}O_{2}$?

Peroxisomes

Peroxisomal _____ are the specific enzymes responsible for breaking down hydrogen peroxide.

catalases

The three primary fiber types making up the cytoskeleton are microtubules, intermediate filaments, and _____.

microfilaments

Microtubules are composed of polymerized arrays of _____ dimers.

$\alpha$- and $\beta$-tubulin

Regarding microtubule polarity, which end is associated with $\alpha$-tubulin?

The minus ($-$) end

Which component of the cytoskeleton is a hollow tube with a diameter of approximately $25\text{ nm}$?

Microtubules

What is the primary function of intermediate filaments within the cell?

They form a flexible scaffolding to resist external pressure.

A clinical deficiency or abnormality in intermediate filaments often manifests as _____ of the skin.

blistering

Microfilaments are primarily composed of the protein _____.

actin

What is the most abundant protein found in mammalian cells?

Actin

Which cytoskeletal component is essential for muscle contraction?

Microfilaments (actin)

Cilia are specialized cellular projections used to propel _____ over epithelial surfaces.

mucus

Primary ciliary dyskinesia results in the impairment of the _____ escalator, leading to airway infections.

mucociliary

The dense RNA region found within most nuclei is called the _____.

nucleolus

What organelle consists of a complex series of tubules and is the site of steroid synthesis and detoxification?

Smooth Endoplasmic Reticulum

Rough Endoplasmic Reticulum is 'rough' because _____ are attached to its membrane.

ribosomes

What is the primary functional role of the Rough Endoplasmic Reticulum?

Protein synthesis (translation) and initial polypeptide folding.

The _____ reticulum is a modified version of the ER integral to muscle movement.

sarcoplasmic

Mammalian ribosomes are composed of two subunits: the _____ and _____ subunits.

$60S$; $40S$

The Golgi apparatus is typically located near which other major organelle?

The nucleus

The 'receiving' side of the Golgi apparatus is known as the _____ face.

cis

What are the three main functions of the Golgi apparatus?

Modification, packaging, and sorting of proteins.

Proteins destined for the plasma membrane, lysosomes, or _____ are processed by the Golgi apparatus.

secretion

The _____ describes the cyclic sequence of events where a parent cell splits into two identical daughter cells.

cell cycle

Which phase of the cell cycle is a 'cell arrest' point where the cell is not actively dividing?

$G_{0}$

During which phase of the cell cycle are the centrioles duplicated?

$G_{1}$ (Gap 1)

How long does the S phase typically take to complete?

Approximately $8\text{ hours}$

In the S phase, DNA is replicated in a _____ fashion.

semi-conservative

After the S phase, each chromosome consists of _____ chromatids.

two

The interval between DNA synthesis and the start of mitosis is the _____ phase.

$G_{2}$

Which phase of the cell cycle is the shortest, lasting approximately $90\text{ minutes}$?

Mitosis

In which phase of mitosis does the nuclear envelope break down?

Prophase

During which mitotic phase do kinetochores first appear at the centromeres?

Prometaphase

What event defines Metaphase in mitosis?

Chromosomes line up at the metaphase plate.

In Anaphase, which specific proteins must break down for sister chromatids to separate?

Cohesin proteins

During Telophase, chromosomes arrive at opposite poles and begin to _____.

decondense

In animal cells, cytokinesis is achieved by a _____ that separates the daughter cells.

cleavage furrow

What is the clinical term for an abnormally high percentage of cells in mitosis within a tissue sample?

High mitotic index

Which two classes of proteins drive the progression of the cell cycle?

Cyclins and Cyclin-Dependent Protein Kinases (CDK)

The $G_{1}/S$ checkpoint monitors the cell's size and _____.

DNA integrity

What is being monitored during the late metaphase (spindle) checkpoint?

Spindle formation and attachment of microtubules to kinetochores.

Which Cyclin-CDK pairing is specific to the $G_{1}$ phase?

$CDK4-6$ and Cyclin D

The transition from $G_{1}$ to S phase is driven by $CDK2$ and _____.

Cyclin E

Which Cyclin-CDK complex drives the cell through the S phase?

$CDK2$ and Cyclin A

Progression through the $G_{2}$ phase is mediated by $CDK1$ and _____.

Cyclin A

The M phase transition is primarily regulated by the pairing of $CDK1$ and _____.

Cyclin B

Chemotherapeutic drugs generally target cells that are _____.

rapidly proliferating

List three types of normal human cells that are often collateral targets of chemotherapy.

Hair follicles, GI mucosa, and male germ cells.

Which class of chemotherapy drugs, including Taxanes and Vinca alkaloids, inhibits the M phase?

Microtubule inhibitors

Methotrexate and 5-fluorouracil belong to which class of drugs that target the S phase?

Antimetabolites

Which chemotherapy drug is known to specifically inhibit the $G_{1}$ phase?

Dactinomycin

Which specific phase of the cell cycle is targeted by the drug Bleomycin?

$G_{2}$ phase

Topoisomerase inhibitors like Etoposide and Irinotecan target the _____ and _____ phases of the cell cycle.

S; $G_{2}$

Give an example of a cell cycle-independent class of chemotherapy drugs.

Alkylating agents (or Anthracyclines/Antitumor antibiotics).

Nitrogen mustards and Nitrosoureas are examples of _____.

Alkylating agents

The $G_{2}/M$ checkpoint specifically monitors for _____ and DNA damage.

DNA synthesis

Identify the primary molecular motor-related structure that moves organelles along the cytoskeleton.

Microtubules

What is the diameter of an intermediate filament?

$10\text{ nm}$

What is the diameter of a microfilament?

$7\text{ nm}$

Which cytoskeletal element consists of several different proteins depending on the cell type?

Intermediate filaments

What specific phase of mitosis involves the lengthening of nonkinetochore spindle fibers to elongate the cell?

Anaphase

True or False: Plant cells form a cleavage furrow during cytokinesis.

False (they form a cell plate).

What is the result when a cell fails to pass a cell cycle checkpoint?

It should trigger apoptosis.

Which organelle is responsible for the sorting of all materials destined for secretion?

Golgi Apparatus

The nuclear envelope is continuous with which other organelle system?

Endoplasmic Reticulum

Which chemotherapy drug acts as a Proteasome inhibitor (targeting the transition between S and $G_{2}$)?

Bortezomib

Cladribine and Cytarabine are examples of which drug class?

Antimetabolites

In the cell membrane, _____ proteins are loosely attached to the surface and are called 'extrinsic'.

peripheral

What is the function of ion channels in the cell membrane?

They permit the passage of ions into or out of the cell when activated.

Which cytoskeletal component is found in the platelets of the blood?

Microtubules

How many protofilaments typically form the hollow tube of a microtubule?

$13$

In which mitotic phase do the centrosomes move toward opposite poles?

Prometaphase

What is the chromosomal composition immediately before the S phase?

Each chromosome is composed of one chromatid.

Distinguish between a nucleoside and a nucleotide based on chemical composition.

A nucleoside consists of a nitrogenous base and a carbohydrate, while a nucleotide adds one or more phosphate groups to that structure.

Which heterocyclic aromatic organic compound family consists of a pyrimidine ring fused to an imidazole ring?

Purines.

Name the two specific nitrogenous bases that belong to the purine family in DNA.

Adenine and Guanine.

Identify the two nitrogenous bases classified as pyrimidines within the DNA structure.

Cytosine and Thymine.

What is the specific structural difference between the ribose sugar in RNA and the deoxyribose sugar in DNA?

Deoxyribose lacks an oxygen atom at the $2'$ carbon position (2-Deoxy-$\beta$-D-ribofuranose).

By what specific linkage are nucleotides joined together to form a DNA chain?

$3'-5'$ phosphodiesterase linkages.

In which direction is DNA always read, replicated, and transcribed?

The $5'$ to $3'$ direction.

How many hydrogen bonds connect a Cytosine-Guanine base pair?

Three hydrogen bonds.

How many hydrogen bonds stabilize the pairing between Thymine and Adenine?

Two hydrogen bonds.

Beyond hydrogen bonding, list three forces that stabilize the DNA double helix.

Van der Waals interactions, hydrophobic properties of nitrogen bases, and base stacking.

What are the 'major and minor grooves' of the DNA double helix?

Exposed sections of the helix that allow interaction with proteins and other molecules.

List the four specific histone proteins that comprise the core of a nucleosome.

$H2A$, $H2B$, $H3$, and $H4$.

What is the composition of the protein complex at the center of a nucleosome?

An octamer consisting of two copies each of histones $H2A$, $H2B$, $H3$, and $H4$.

Define 'solenoid structures' in the context of DNA packaging.

Helical, tubular coils formed by strings of wound nucleosomes.

Which nitrogenous base is unique to RNA, replacing the thymine found in DNA?

Uracil.