EXSC 223 Exam 1 Ray Thompson

Principle of Complementarity

function always reflects structure

Physiology uses gradients

Level/difference of two points; everything moves high to low unless manufactured for vice versa

Regulate protein function by regulating its shape

if the shape of the protein is altered, so is the function; ie. contracting muscles

what is essential to restoring homeostasis when disrupted?

negative feedback

negative feedback

regulatory mechanism where a stimulus causes a response that opposes the original stimulus, bringing the system back to a stable state

example of negative feedback

sweating, shivering

sodium potassium pump

A special transport protein in the plasma membrane of animal cells that transports sodium out of the cell and potassium into the cell against their concentration gradients.

the cell theory

idea that all living things are composed of cells, cells are the basic units of structure and function in living things, and new cells are produced from existing cells

three major parts of a eukaryote

nucleus, cytoplasm, plasma membrane

what do cells do all day while you are working?

-segregate (separate internal from external)

-transport and digest (membrane trafficking-moving things across membrane)

-identify alien invaders (distinguish self from non-self)

-internal support (cytoskeleton)

-hold hands (cell to cell adhesion)

-communicate (between cells)

-build/remodel/demolish (protein synthesis and degradation)

-clone (cell replication through mitosis and cytokinesis)

what is the plasma membrane made up of?

phospholipids (phospholipid bilayer)

what are phospholipids made up of?

-glycerol, 2 fatty acids, and a phosphate group

-hydrophilic head and hydrophobic tail

hydrophilic

Attracted to water

hydrophobic

Aversion to water

what is cholesterol's role in the plasma membrane?

stability, helps remain flexible at cool temperatures

what are glycolipids? what is their function?

carbohydrates (sugar groups) attached to lipids, they attract water to the outside of the cell, cell-cell recognition, self identification

fluid mosaic model

describes the cell membrane as a dynamic structure, like a mosaic of molecules that can move and change position

peripheral proteins

The proteins of a membrane that are not embedded in the lipid bilayer

integral proteins

proteins that are embedded in the hydrophobic interior of the lipid bilayer

what are glycoproteins? what is their function?

membrane proteins with branching sugars; they act as receptors for hormones and neurotransmitters

What is the glycocalyx?

"sugar coat"; acts as a protective shield, preventing direct contact between cells and the external environment.

Passive Transport (Diffusion)

A process that requires no energy to move molecules down their concentration gradient(from high to low concentration)

Active Transport

the movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.

what is the difference between diffusion and osmosis?

diffusion is movement of solute from high to low concentration, osmosis is the movement of water from low to high solute concentration

isotonic solution

Equal solute concentration inside and outside cell. Cell would retain normal size inside of this solution

hypertonic solution

Solute concentration is greater than that inside the cell; cell loses water so it would shrink

hypotonic solution

Solute concentration is less than that inside the cell; cell gains water and will expand/burst

primary active transport

active transport that relies directly on the hydrolysis of ATP (breaking a bond in ATP to release energy).

secondary active transport

does not use ATP directly, it uses a gradient as energy source. the gradient is potential energy

exocytosis (vesicular transport)

release of substances out a cell by the fusion of a vesicle with the membrane. how we get bulk out of the cell

endocytosis

a cellular process where a cell takes in substances from its surroundings by engulfing them with its cell membrane

transcytosis

moving substances into, across, and then out of a cell

receptor-mediated endocytosis

binding of ligands to receptors triggers vesicle formation

what is a ligand?

any molecule that binds specifically to a receptor site of another molecule

clathrin

protein that coats the inward-facing surface of the plasma membrane and assists in the formation of specialized structures, like coated pits, for phagocytosis

caveolae

bring calcium into the cell, form complex shapes, involved in endocytosis

phagocytosis

a process where cells engulf and digest particles, such as bacteria, dead cells, or debris

pinocytosis

process by which a cell takes in liquid from the surrounding environment (basically the cell drinking)

What does the cytoskeleton consist of?

microtubules, microfilaments, intermediate filaments

function of microtubules

serve as intracellular highways for transporting vesicles and organelles; required for cellular locomotion via flagella and cilia; made of globular protein called tubulin

function of microfilaments

reinforce plasma membrane and organize proteins associated with it

function of intermediate filaments

support cell shape and fix organelles in place, maintain structure

centrioles

small, cylindrical structure found in animal cells that helps organize the movement of chromosomes during cell division. It also plays a role in forming structures like cilia and flagella, which help cells move.

tight junctions

impermeable junction that encircles the cell (water tight seal)

desmosome

junctions that are present when something is under mechanical stress; ie. rubbing your hand against the inside of your purse is mechanical stress

gap junction

-allows chemical substances to pass between cells (connect the internal environment between two adjacent cells)

-very abundant in the heart

kinesin and dynein

motor proteins that help with transcytosis; associated with microtubules

mitochondria

site of oxidative metabolism, where oxygen goes in order to help us produce ATP

nuclear envelope

layer of two membranes (phospholipid bilayers) that surrounds the nucleus of a cell

nucleolus

Found inside the nucleus; produces ribosomes and RNA

chromatin

Substance found in eukaryotic chromosomes that consists of DNA tightly coiled around histones

what is the only cell in the human body without a nucleus?

erythrocytes (red blood cells)

what is the difference between an RNA nucleotide and a DNA nucleotide?

no oxygen on carbon #2 on the ribose sugar in DNA

(DNA= OH H, RNA= OH OH)

why do we use RNA for chemical energy?

it's structurally simple, easily recycled, and stores energy efficiently in its phosphate bonds.; unlike DNA which is not easily replaced and is more structurally complex

nucleosome

Bead-like structure in chromatin, composed of DNA wrapped around a core of histone proteins; DNA packing unit, enhances integrity of DNA

histone proteins

proteins that bind DNA and wrap it into chromosomes; they prevent damage to the DNA

Telomeres are:

chromosome end structures required for complete replication of chromosomes

Telomorase is:

enzyme that adds DNA sequences to the telomeres to prevent them from shortening during cell division

genes are:

segments of DNA that code for specific proteins

promoters are:

DNA sequences located at the beginning of a gene that signal RNA polymerase where to start transcription

transcription

the process by which a cell makes an RNA copy of a gene's DNA sequence.

mRNA

messenger RNA; type of RNA that carries instructions from DNA in the nucleus to the ribosome

tRNA

transfer RNA; type of RNA that carries amino acids to the ribosome

rRNA

ribosomal RNA; type of RNA that makes up part of the ribosome

translation

Process by which mRNA is decoded and a protein is produced

initiation (transcription)

the first step where RNA polymerase binds to the promoter region of DNA and begins to unwind the DNA strands to start RNA synthesis.

elongation (transcription)

the stage where RNA polymerase moves along the DNA template strand, adding complementary RNA nucleotides to build the growing RNA molecule.

termination (transcription)

the final step where RNA polymerase reaches a specific DNA sequence that signals the end of the gene, causing it to release the newly made RNA and detach from the DNA

initiation (translation)

the process where the ribosome assembles around the mRNA and the first tRNA, starting protein synthesis at the start codon (usually AUG).

elongation (translation)

the stage where the ribosome moves along the mRNA, and tRNAs bring amino acids that are joined together to form a growing polypeptide chain.

termination (translation)

when the ribosome reaches a stop codon on the mRNA, causing the release of the completed polypeptide

function of ribosomes

site of protein synthesis, they select appropriate amino acids to make peptide chain

function of Rough ER

synthesizes and processes proteins that are usually destined for secretion or for use in the cell membrane

free ribosomes

ribosomes suspended in the cytosol, associated with the synthesis of cytosolic proteins

bound ribosomes

attached to the outside of the endoplasmic reticulum, translate secreted proteins

signal recognition particle (SRP)

a protein-RNA complex that recognizes and guides newly made proteins with a signal sequence to the rough ER for proper processing

function of golgi apparatus

Modify, sorts and packages proteins and other materials from the ER for storage in the cell or secretion outside the cell

proteolysis

breakdown of soluble cytosolic proteins into amino acids.

what is ubiquitin?

a small protein that tags damaged or unneeded proteins for degradation by the cell's recycling system

what is a proteasome?

barrel-shaped protein complex that degrades damaged or unnecessary proteins tagged for destruction with ubiquitin

function of Smooth ER

Make membrane lipids, detoxification of drugs, breakdown of stored glycogen

mitosis

nuclear division; pulls apart sister chromatids

G1 phase

The first growth phase of the cell cycle, consisting of the portion of interphase before DNA synthesis begins; proteins are produced in order for cells to survive

G0 phase

A nondividing state in which a cell has left the cell cycle, cells that do not replicate after G1 (amitotic)

S phase

DNA replication, chromosomes are doubled

semi-conservative replication

the process by which DNA is copied, producing two molecules each with one original (parental) strand and one newly synthesized strand

okazaki fragments

Small fragments of DNA produced on the lagging strand during DNA replication, joined later by DNA ligase to form a complete strand.

leading strand

The new continuous complementary DNA strand synthesized along the template strand in the mandatory 5' to 3' direction.

centromeres are:

regions that attach chromosomes

kinetochore

region on the centromere that links each sister chromatid to the mitotic spindle.

G2 phase

The second growth phase of the cell cycle, produces necessary proteins for the cell to pass through mitotic phase

early prophase

chromatin is condensing into chromosomes, nucleolus starts to break down

late prophase

The nuclear envelope breaks up, allowing the mitotic spindle to attach to the sister chromatids

metaphase

Chromosomes line up in the middle of the cell, mitotic spindles push them to the center

anaphase

sister chromatids are pulled apart to opposite poles, mitotic spindles disassemble and shorten

telophase

nuclear envelope reforms and encapsulates the chromosomes

Ubiquitin-proteasome pathway

proteins are poly-ubiquinated and become a target for the proteasome, and are then degraded

the functional characteristics necessary to maintain life in humans

maintaining boundaries, movement, responsiveness, digestion, metabolism, excretion, reproduction, growth

Survival needs of the body

nutrients, oxygen, water, normal body temperature, appropriate atmospheric pressure

describe the relationship between homeostatic imbalance and disease

Homeostatic imbalance disrupts the body's internal stability, leading to the development or progression of disease by impairing normal physiological functions.