L02 L03 The Cell

Learning Objective 1: Identify typical cellular components and organization

What is the approximate total number of cells in the human body?

Roughly 1×10¹⁴ cells

Learning Objective 1: Identify typical cellular components and organization

What are the two principal categories of cells in the human body?

Sex cells and somatic cells.

Learning Objective 1: Identify typical cellular components and organization

What are the human sex cells?

Sperm in males and oocytes in females

Learning Objective 1: Identify typical cellular components and organization

How many copies of each chromosome do mature sex cells carry?

One copy

Learning Objective 1: Identify typical cellular components and organization

What defines somatic cells?

All non-sex cells in the human body

Learning Objective 1: Identify typical cellular components and organization

What is the exterior membrane of the cell called?

Plasmalemma (or cell membrane/plasma membrane).

Learning Objective 1: Identify typical cellular components and organization

What term describes all the material contained within the plasmalemma?

Cytoplasm

Learning Objective 1: Identify typical cellular components and organization

What two primary components comprise the cytoplasm?

Cytosol and organelles

Learning Objective 1: Identify typical cellular components and organization
What percentage of a cell's total weight is made up of proteins?

15–30%.

Learning Objective 1: Identify typical cellular components and organization

Which ion is found in high concentration within the cytosol?

K⁺ Potassium

Learning Objective 1: Identify typical cellular components and organization

Which ion is found in high concentration in the extracellular fluid?

Na⁺ Sodium

Learning Objective 1: Identify typical cellular components and organization

What are the two broad structural categories of organelles?

Nonmembranous organelles and membranous organelles.

Learning Objective 1: Identify typical cellular components and organization
What defines nonmembranous organelles?

Organelles that lack a membrane and are always in contact with the cytosol.

Learning Objective 1: Identify typical cellular components and organization
Which six structures are classified as nonmembranous organelles?

Cytoskeleton,

Centrioles

Cilia

Microvilli

Flagella

Ribosomes.

Learning Objective 1: Identify typical cellular components and organization
Which six structures are classified as membranous organelles?

Mitochondria

Endoplasmic reticulum

Nucleus

Golgi apparatus

Lysosomes

Peroxisomes.

Learning Objective 1: Identify typical cellular components and organization

What are the four major components of the cytoskeleton?

Microfilaments

intermediate filaments

thick filaments

microtubules.

Learning Objective 1: Identify typical cellular components and organization
What protein subunit polymerizes to form microtubules?

Tubulin

Learning Objective 1: Identify typical cellular components and organization

What structural arrangement defines a centriole?

Nine microtubule triplets (9+0 array).

Learning Objective 1: Identify typical cellular components and organization

What structures make up a centrosome?

pair of centrioles oriented at right angles to one another.

Learning Objective 1: Identify typical cellular components and organization

What structural arrangement defines a cilium?

Nine pairs of microtubules surrounding a central pair (9+2 array).

Learning Objective 1: Identify typical cellular components and organization

What are the two subunit components of a ribosome?

A small ribosomal subunit and a large ribosomal subunit.

Learning Objective 1: Identify typical cellular components and organization

What diameter do ribosomes typically measure?

Approximately 25 nm

Learning Objective 1: Identify typical cellular components and organization

What structural feature surrounds the cell nucleus?

double-membrane nuclear envelope

Learning Objective 1: Identify typical cellular components and organization

What size limit governs passive molecular passage through nuclear pores?

Molecular weight less than 44 kDa.

Learning Objective 1: Identify typical cellular components and organization

What are cisternae?

Hollow tubes, flattened sheets, or rounded chambers within the endoplasmic reticulum and Golgi apparatus

Learning Objective 1: Identify typical cellular components and organization

What structural feature distinguishes rough ER from smooth ER?

Fixed ribosomes attached to its membrane.

Learning Objective 1: Identify typical cellular components and organization

Which face of the Golgi apparatus receives transport vesicles?

forming (cis) face

Learning Objective 1: Identify typical cellular components and organization
Which face of the Golgi apparatus releases secretory and membrane renewal vesicles?

maturing (trans) face.

Learning Objective 2: Relate the structure of cellular components to their function

What are the four major functions of the plasmalemma?

sensitivity

structural support

Physical isolation

regulation of exchange with environment.

Learning Objective 2: Relate the structure of cellular components to their function

Which lipid-soluble substances pass directly through the plasmalemma lipid bilayer via simple diffusion?

Lipids

lipid-soluble molecules

soluble gases (O₂ and CO₂).

Learning Objective 2: Relate the structure of cellular components to their function

How do water, small water-soluble molecules, and ions cross the plasmalemma?

membrane channels.

Learning Objective 2: Relate the structure of cellular components to their function

How do large, channel-impermeable molecules cross the plasmalemma?

carrier mechanisms.

Learning Objective 2: Relate the structure of cellular components to their function

What primary functions do microfilaments (actin) serve in the cell?

Anchoring cytoskeleton to integral proteins

anchoring plasmalemma to cytoplasm

stabilizing membrane protein position

Learning Objective 2: Relate the structure of cellular components to their function

What primary functions do intermediate filaments (such as keratin) serve?

cell strength

stabilizing organelle position

transporting material within cytosol.

Learning Objective 2: Relate the structure of cellular components to their function
What major cell functions are driven by microtubules?

cell shape

cell division,

cell movement

Learning Objective 2: Relate the structure of cellular components to their function

What movement pattern does a cilium execute to move materials over a cell surface?

A stiff power stroke followed by a flexible return stroke parallel to the cell surface.

Learning Objective 2: Relate the structure of cellular components to their function

What primary function is carried out by ribosomes?

Protein synthesis

Learning Objective 2: Relate the structure of cellular components to their function

Where do free ribosomes synthesize proteins?

Directly into the cytosol.

Learning Objective 2: Relate the structure of cellular components to their function

Where do fixed ribosomes synthesize proteins?

Into the endoplasmic reticulum.

Learning Objective 2: Relate the structure of cellular components to their function

What proportion of cellular ATP is produced by mitochondria?

95 percent

Learning Objective 2: Relate the structure of cellular components to their function

What metabolic structures are contained within the mitochondrial matrix?

inner network of enzymes for cellular energy production.

Learning Objective 2: Relate the structure of cellular components to their function

What primary functions does the cell nucleus serve?

Storage and processing of genetic information

control of metabolism

control of protein synthesis.

Learning Objective 2: Relate the structure of cellular components to their function

What specific function takes place within the nucleolus?

Synthesis of rRNA and assembly of ribosomal subunits.

Learning Objective 2: Relate the structure of cellular components to their function

What primary substances are synthesized by the endoplasmic reticulum?

Carbohydrates, steroids, and lipids.

Learning Objective 2: Relate the structure of cellular components to their function

What additional functional roles does the endoplasmic reticulum perform?

Modifying translated polypeptides

storing absorbed substances

transporting molecules

inactivating cellular toxins.

Learning Objective 2: Relate the structure of cellular components to their function

What is the primary function of the smooth endoplasmic reticulum?

Lipid, steroid, and carbohydrate synthesis, as well as calcium ion storage.

Learning Objective 2: Relate the structure of cellular components to their function

What is the primary function of the rough endoplasmic reticulum?

Modification and packaging of newly synthesized proteins.

Learning Objective 2: Relate the structure of cellular components to their function

What are the three main functions of the Golgi apparatus?

Synthesis/packaging of secretions, packaging special enzymes for cytosolic use, and renewal/modification of the plasmalemma

Learning Objective 2: Relate the structure of cellular components to their function
What organelles are formed directly through the coordination of ER enzymes and Golgi apparatus packaging?

Lysosomes

Learning Objective 2: Relate the structure of cellular components to their function
What is the primary function of a primary lysosome fusing with a damaged organelle or endosome?

Intracellular removal and breakdown of damaged organelles or foreign materials

Learning Objective 2: Relate the structure of cellular components to their function
What process occurs when lysosomal membranes break down following cell injury or death?

Autolysis (self-digestion of the cytoplasm).

Learning Objective 2: Relate the structure of cellular components to their function
What primary enzymes are contained within peroxisomes?

Oxidases and degradative enzymes.

Learning Objective 2: Relate the structure of cellular components to their function

What major metabolic processes take place in peroxisomes?

Catabolism of fatty acids/organic compounds, production and conversion of hydrogen peroxide, and neutralization of digestive toxins.

Learning Objective 3: Compare and contrast structural and functional differences among different cell types

How is the endoplasmic reticulum modified in skeletal muscle cells?

It is specialized as the sarcoplasmic reticulum to store high levels of calcium ions.

Learning Objective 3: Compare and contrast structural and functional differences among different cell types

Which cytoskeletal filaments within skeletal muscle cells interact to enable contraction?

Myosin (thick filaments) and actin (microfilaments).

Learning Objective 3: Compare and contrast structural and functional differences among different cell types

What structural adaptation in skeletal muscle cells provides the massive ATP needed for contraction?

A high density of mitochondria

Learning Objective 3: Compare and contrast structural and functional differences among different cell types
What specialized cytoskeletal components support the long cellular processes and shape of dendrites and axons in neurons?

Microtubules and neurofilaments

Learning Objective 3: Compare and contrast structural and functional differences among different cell types
What are Nissl bodies in neurons?

Specialized clusters of rough endoplasmic reticulum

Learning Objective 3: Compare and contrast structural and functional differences among different cell types
How is the sperm cell structurally tailored for its primary function?

Its structure is optimized entirely for mobility to deliver its nucleus to an oocyte.

Learning Objective 3: Compare and contrast structural and functional differences among different cell types
Where are mitochondria localized in a sperm cell to power flagellar movement?

Wrapped in a spiral around the midpiece.

Learning Objective 3: Compare and contrast structural and functional differences among different cell types

What structural feature forms the tail of a sperm cell to drive propulsion?

A single flagellum.

Learning Objective 3: Compare and contrast structural and functional differences among different cell types

What structure forms the brush border of intestinal epithelial cells?

Microvilli

Learning Objective 3: Compare and contrast structural and functional differences among different cell types
What is the primary functional advantage of the microvilli/brush border on intestinal epithelial cells?

It vastly increases surface area to maximize absorption of extracellular materials.

Learning Objective 3: Compare and contrast structural and functional differences among different cell types

How many copies of each chromosome do somatic cells carry?

Two copies (diploid).

Learning Objective 3: Compare and contrast structural and functional differences among different cell types

Which cytoskeletal component dictates plasmalemma integral protein position?

Microfilaments (actin).

Learning Objective 3: Compare and contrast structural and functional differences among different cell types

Why were thick filaments skipped when covering nonmembranous organelles common to all body cells?

Thick filaments (myosin) are specialized components found predominantly in muscle cells rather than general body cells.

Learning Objective 3: Compare and contrast structural and functional differences among different cell types

How many copies of a chromosome must be delivered by a sperm cell to an oocyte?

One copy. Is a sperm cell really a cell? Yes, it is a highly specialized haploid sex cell (gamete).