Block 2 Exam KIN223

bruh

Light microscopy

two dimensional by passing visible light through the specimen with colored dyes.

Transmission electron microscopy

uses a beam of electrons to “illuminate” the specimen stained with heavy metals and produces a two-dimensional image.

Scanning electron microscopy

Produces a three dimensional image and the electron beam is moved across the surface and generates a digital image.

Irregular-shaped cell

Nerve cells

Biconcave disc cell

Red blood cells

Cube-shaped (Cuboidal) cell

Kidney tubule cells

Column-shaped (Columnar) cell

Intestinal lining cells

Spherical cell

cartilage cells

Cylindrical

Skeletal muscle cells

Three main structural features of a cell

plasma membrane, nucelus, cytoplasm

Cell inclusions

not considered organelles, they are clusters of a single type of molecule. These molecules are continuously removed and added from inclusions. Examples include pigments and nutrient stores.

The general functions that a cell must perform:

maintain integretiy and shape of a cell, obtrain nutriewnts and form chemical building blocks, dispose of waste

Lipid components of a the plasma membrane:

Phospholipids, Cholesterol, Glycolipids

Two types of memrbane proteins in the plasma membrane:

Integral Proteins & Peripheral Proteins

6 major roles played by membrane proteins:

Transport proteins, Cell surface receptors, Identity markers, Enzymes, Anchoring Sites, Cell-adhesion proteins

Diffusion

movement of ions or molecules DOWN their concentration gradient. Occurs due to kinetic energy of the ions or molecules.

Simple Diffusion

small and nonpolar molecules move into or out of a cell down their concentration gradient by simple diffusion. These molecules move unassisted across the plasma membrane. Dependent on concentration gradient.

Channel-mediated diffusion

Channels are typically built for one type of ion. The channel is either a leak channel (continuously open) or a gated channel. Gated channels are typically closed and respond to certain stimuli to open.

Carrier-mediated diffusion

movement of polar molecules (glucose, amino acids) across the plasma membrane. Induces the carrier protein protein to change shapes and carry the molecule to the other side.

Osmosis

the passive movement of water (not solutes) across a semipermeable (selectively permeable) membrane.

Isotonic

same concentration as cytosol

Hypotonic

solution has a lower concentration  of solutes and a higher concentration of water than the cell’s cytosol

Hypertonic

solution has a higher concentration of solutes, and thus a lower concentration of water than the cell’s cytosol.

Primary active transport

uses energy derived from the breakdown of ATP. This results in an additional phosphate group which can attach to a membrane transport pump that subsequently changes the shape. This process is called phosphorylation.

Secondary active transport

also called cotransport, or coupled transport. Sodium and Calcium ions bind on opposite sides of the membrane (known as the antiport) and are moved in opposite directions one at a time. Symports move substances in the same direction.

Exocytosis

Large amounts of substances are secreted from the cells. Macromolecules are too large to move across the plasma membrane and need to be exported with the use of vesicles. Fusion with the plasma membrane is the energy-requiring step.

Endocytosis

Cellular uptake of either large substances or large amounts of substances from the external environment. Essentially the opposite of exocytosis but instead the plasma membrane folds inwards into the cytosol.

Phagocytosis

also known as cellular eating, occurs when a cell engulfs or captures a large particle external to the cell by forming membrane extensions that are called pseudopodia and surround the particle.

Pinocytosis

also known as cellular drinking is the incorporation of number droplets of interstitial fluid into the cell in small vesicles as many regions of the plasma membrane invaginate.

Receptor-mediated endocytosis

occurs when specific molecules bind to receptors in the plasma membrane and bring in molecules into the cell. Molecules called ligands that are within the interstitial fluid attach to their distinct integral membrane protein receptors. Following the ligand bonding, a special membrane accumulate called clathrin proteins bind together and invaginate to make a clathrin-coated pit.

Cellular condiions for maintaing RMP

• Unequal distribution of ions and charged molecules across the plasma membrane.

• The amount of K+ and Na+ must be in opposite places (More K+ in the cytosol and more Na+ in the interstitial fluid) and result in Na+/K+ pumps

• More positive charge on the outside than on the inside and the inside is more negatively charged.

Three general mechanisms of resposne to the binding of a ligand with a receptor

Channel-linked receptors, Enzymatic receptors, G protein-coupled receptors

Lysosomes

participate in digestion of unneeded or unwanted biological macromolecules.

Perixosomes

small, membrane-enclosed, spherical sacs that contain over 50 different enzymes that vary by cell type. Function in both digestion and synthesis of molecules.

Centrosome

typically close to the nucleus. The primary function of the centrosomes is to organize the cytoskeleton’s microtubules. Best known for its cellular division.

Proteasomes

maintain order within the cell by digesting abnormal and unwanted cellular proteins.

Transcription: Intiation

Promoter region signals where the gene starts and what strand to use as a template.

Transcription: Elongation

RNA polymerase then begins to move along the DNA strand and reads the DNA template. It then adds complementary RNA nucleotides to growing RNA molecule as it moves down the gene.

Transcription:Termination

A specific sequence indicates the end of the gene. RNA polymerase recognizes the termination and releases the termination sequence from DNA.

Required structures for transcription

• DNA

• Ribonucleotides

• RNA polymerase

Required structures for translation

• mRNA

• tRNA

• Large numbers of free amino acids

Start codon

always contain the three bases AUG and signals where protein synthesis begins along the mRNA strand.

Stop codon

within the mRNA strand follows the codons used to assemble the new protein. These three codons do not code for an amino acid. They serve as the point where the reading of mRNA ends.

Regular codon

direct the assembly of amino acid to be added to the newly forming protein strand.

Chromatin

is the loose, uncoiled form of DNA and proteins and it is present during interphase when the cell is not dividing.

Chromosomes

are tightly coiled and condensed forms of chromatin, and they are present during mitosis and meiosis when the cell is actively dividing.

Growth 1 Phase

normal cell functions and growth.; preparation for S phase

Synthesis Phase

DNA replication - result in two identical sister chromatids

Growth 2 Phase

extra growth and prepares for mitosis

Four stages of mitosis

• Prophase: chromosomes condense, spindle forms, nuclear envelope breaks down.

• Metaphase: chromosomes align at the cell’s center

• Anaphase: Sister chromatids are pulled apart to opposite sides of the cell.

• Telophase: Nuclear envelopes reform, chromosomes decondense

Cytokinesis

Cytoplasm divides, resulting in two daughter cells

Apoptosis

cells commit suicide due to being injured or unhealthy. It’s usually always easier to kill a cell than repair it.

common features of the epithelial tissue

• Cellularity

• Polarity

• Attachment to a basement membrane

• Avascularity

• Extensive innervation

• High regeneration capacity

Cellularity

composed of almost entirely tightly packed cells. There is a minimal amount of extracellular matrix between the cells.

Polarity

has an apical surface which is exposed either to the external environment or to some internal body space. Each epithelium has a basal surface where it is attached to a basement membrane with underlying connective tissue.

Attachment to a basement membrane

bound to a basal surface to a thin basement membrane. Made up of collagen, glycoproteins, and proteoglycans and together act as glue.

Avascularity

All epithelial tissues lack blood vessels. Nutrients are obtained by the apical surface or the diffusion across the basal surface from blood vessels in the underlying connective tissue.

Extensive innervation

Epithelia are richly innervated (supplied with nerves) to detect changes in the environment at that body or organ region.

High regeneration capacity

Epithelial cells under cell division frequently. This characteristic allows tissue to regenerate itself at a high rate.

Four functions of the epithelial tissues

• Physical protection

• Selective permeability

• Secretions

• Sensations

Physical Protection

Epithelial tissues protect both external and internal surfaces from dehydration, abrasion, and destruction by physical, chemical, and biological agents.

Selective permeability

All substances must pass through the epithelium and act as the body’s gatekeeper. Exhibits a range of permeability, sometimes might be non-permeable or promote permeability for the passage of molecules and ions.

Secretions

epithelium specialized to produce and release secretions. These cells form glands.

Sensations

epithelial cells innervated by sensory nerve endings to detect or respond to stimulus.

Simple epithelium

one layer of cells

Simple squamous

one layer of flat cells

Simple cuboidal

one layer of cells about as tall as wide

Simple columnar

one layer of tall, narrow cells

Pseudostratified columnar

one layer of tall cells that appeared stratified

Stratified epithelium

two or more layers of cells

Stratified squamous

multiple layers of flattened cells

Stratified squamous: Keratinized

 superficial cells are dead

Stratified squamous: Nonkeratinized

superficial cells are living

Stratified cuboidal

two or more layers, cells about as tall as wide

Stratified columnar

two or more layers of tall, narrow cells

Transitional

multiple layers of cells that change shape when stretched

Simple squamous FN/L

allows for rapid diffusion and filtration, secretion in serous membrane and can be found in alveoli and lining of lumen blood vessels.

Simple cuboidal FN/L

absorption and secretion; forms secretory tissue of most glands and small ducts and can be found in the kidney tubules and thyroid gland follicles.

Nonciliated simple columnar epithelium FN/L

 absorption and secretion and located in most gastrointestinal tract.

Ciliated simple columnar epithelium FN/L

secretion of mucin and movement of mucus along apical surface of epithelium by cilia and can be found in the uterine tubes.

Ciliated Pseudostratified columnar epithelium FN/L

protection; secretion of mucin and movement of mucus along apical surface of epithelium by cilia and can be found in the larynx and trachea.

Nonciliated Pseudostratified columnar epithelium FN/L

protection and can be found in the rare-lining of the male urethra

Keratinized stratified squamous epithelium FN/L

protection of underlying tissue from abrasion and is located in the epidermis of the skin.

Nonkeratinized stratified squamous epithelium FN/L

protection of underlying tissue from abrasion and can be found in the oral cavity and the lining of the vagina.

Stratified cuboidal epithelium FN/L

protection and secretes and can be found ducts of most exocrine glands and ovarian follicles.

Stratified columnar epithelium FN/L

protects and secretes and can be found in the large ducts of salivary glands.

Transitional epithelium FN/L

accommodates urine volume changes in the urinary bladder, ureters, and part of the urethra and can be found in the urinary bladder.

Endocrine glands

lack ducts and secrete hormones into the blood and are transported throughout the body. Hormones act as chemical messengers to influence cell communication. Thyroid and adrenal glands are examples

Exocrine

glands typically originate from an invagination of epithelium that burrows into the underlying connective tissue. Maintain their connection with epithelial surface by means of a duct, and epithelium-lined tube through which the gland secretions are discharged onto the epithelial surface. Examples include sweat, mammary, and salivary glands.

Merocrine gland

glands package their secretions into secretory vesicles and release the secretions by exocytosis. Ex: salivary glands

Apocrine gland

glands produce their secretory material when the cell's apical portion pinches off, releasing cytoplasmic content. Ex: mammary glands

Holocrine gland

glands are formed from cells that accumulate a product and the entire cell disintegrates. A holocrine secretion if a viscous mixture of both cell and product fragments. The ruptured dead cells are continuously replaced. Ex: sebaceous glands

Fibroblasts

are flat cells with tapered ends and are the most abundant cells. They produce the fibers and ground substances.

Adipocytes

fat cells appear in small clusters within some types of connective tissue. An abundance of these cells make adipose connective tissue

Mesenchymal

a type of embryonic stem cell within connective tissue. If damaged, these cells will divide.

Fixed macrophages

irregularly shaped cells that are derived from a type of leukocyte called a monocyte. They are scattered throughout the matrix and engulf any damaged cells or pathogens.

Protein fibers

Connective tissue that strengthens and support the tissue, and include: collagen fibers, reticular fibers, and elastic fibers

Collagen fibers

cable-like long protein fibers that are strong, flexible, and resistant to stretching. Collagen comprises 25% of the body’s protein and appears white in fresh tissue. In stained sections they appear pink. Found in tendons and ligaments.

Reticular fibers

similar to collagen fibers but much thinner. They act as an interwoven framework that is tough but flexible. They are abundant in the stroma and can be found in the spleen and liver.

Elastic fibers

protein elastin and recoil and stretch easily. Have a yellowish color. Most abundant in the skin, arteries, and lungs to allow them to return to their shape.