Physiology 1

Define cytosol

The liquid component of the cytoplasm that surrounds intracrllular organelles

What 5 substances make up the cell?

-Water

-Lipids

-Proteins

-Carbohydrates

-Ions

Define cytoplasm

All contents of a cell except the nucleus. It includes all organelles and cytosol.

What is the main fluid medium for most cells?

Water

What substances fully dissolve in water in cells?

Salts

Sugars

amino acids

gases

What substances are suspended as solid particles or aggregates in cells? Why?

-Proteins or lipids

-They do not fully dissolve in water

What does water facilitate for dissolved and suspended substances within cells?

Movement and reactions

What three ways do chemical reactions occur in cells?

-Among dissolved chemicals in water

-At surface of suspended particles (like proteins or organelles)

-Within cellular membranes

What cells do not have water as main fluid medium? What is main fluid medium in these cells?

Fat cells (adipocytes)

-95% of cell is fat

What essential processes do the chemical reactions in cells drive?

-Metabolism

-Signaling

-Energy Conversion

What is the key component of cells?

Lipids

What cellular structures do lipids make up?

-Plasma membrane

-Nuclear membrane

-ER

-Golgi

-Endosomes

-Lysosomes

Is the diversity of lipids on the same level as the diversity of proteins?

Yes

What form cell membranes?

Phospholipids and cholesterol

Why are phospholipids and cholesterol good for forming membranes/barriers?

They are hydrophobic (insoluble in water)

How do cells store excess lipids?

Lipid droplets

What are lipid droplets used for?

Membrane synthesis and/or food storage

What are adipocytes specialized for?

lipid storage

Are triglycerides found in some cells?

Yes

What is 95% of the adipocytes mass?

Triglycerides

What is the bodys main storehouse for energy giving nutrients?

Triglycerides in adipocytes

What do proteins mediate?

All physiological changes in a cell

What is the second most abundant substance in a cell?

Proteins

What determines a proteins function?

3-dimensional shape

How does protein 3-dimensional shape determine function?

-Bind other molecules very specifically (lock and key model)

-Can change shape which alters binding properties and function

Proteins can be ____ or _____?

Structural or Functional

What are structural proteins? examples?

Proteins that form cellular structures

-Cytoskeleton and intracellular junctions

What are functional proteins? examples?

Proteins that participate/preform cellular activities

-Enzymes, transport proteins and signaling proteins

What are ions?

charged molecules

What get along well with water? why?

Ions

-they are hydrophilic

What do ions do?

Provide inorganic chemicals for cellular reactions

What are ions necessary for?

Operation of some cellular mechanisms like the transmission of electrochemical impulses in nerve and muscle cells

What ions are in higher quantities inside the cell?

-Potassium (K+)

-Magnesium (Mg2+)

-Phosphate (Po3-)

-Sulfate (So42-)

What ions are in higher quantities outside the cell?

-Sodium (Na+)

-Chloride (Cl-)

-Calcium (Ca2+)

-Bicarbonate (HCO3-)

Which is more negative inside or outside the cell? Which is more positive?

Inside is more negative

Outside is more positive

Which of the main 5 substances that make up a cell have little structural function?

Carbohydrates

What are carbohydrates always in combination with?

Lipids and proteins

What do carbohydrates play a major role as?

A source of energy

Are small or large amounts of carbohydrates stored inside cells?

Small

What can carbohydrates be stores as inside cell?

Glycogen

How is carbohydrates readily available to cells for energy is little is stored inside cells?

Glucose from extra cellular fluid (ECF)

What 3 components make up the nucleus?

-Genetic material

-Nucleolus

-Nuclear membrane or envelope

What two forms can genetic material be in nucleus? Define each.

-Chromatin: loosely packed DNA spread all over nucleus

-Chromosomes: densely packed DNA for cell division

Which DNA is the working DNA?

Chromatin

What is a nucleolus?

An accumulation of large amounts of ribosomal RNA and proteins in nucleus

What is function of nucleolus?

Help to synthesize ribosome subunits

How are ribosome subunits made in nucleolus exported to cytoplasam?

Through nuclear pores where join together in cytoplasam

How many nucleolus do cells usually have in nucleus?

1 to 3

Describe the nuclear membrane or envelope?

Made of phospholipids and is penetrated by several nuclear pores. The nuclear membrane is continuous with the rough ER

What is ribosome function?

Site of protein synthesis as it translates mRNA into polypeptide chains

Where locate ribosomes?

Free in cytoplasm or bound to rough ER

What is function of free ribosomes?

produce cytoplasmic proteins

What is function of bound ribosomes?

Produce secretory and membrane proteins

What is ribosome made of?

Large and small subunits that are made of rRNA and proteins. The subunits join during protein synthesis and come apart when the process is complete

What is a polysome?

Multiple ribosomes attached to the same mRNA strand during protein synthesis

Describe rough ER?

A netlike labyrinth of branching tubules and flattened sacks throughout cytosol that form the rough ER cisternal space

What is rough ER continuous with?

Outer nuclear membrane

What is the central/main role of the rough ER?

Synthesis of membrane proteins and proteins that will be contained in a vesicle

What are the three protein types synthesized by rough ER?

-Membrane proteins

-Secretory proteins

-Lysosomal proteins

What called rough ER? What can it also be called?

Because have ribosomes attached

-can be called granular ER

How do ribosomes work with rough ER?

After ribosome identify the mRNA of a secretory protein ribosomes will move to RER to build the protein in the RER cisternal space

What is smooth ER often continous with?

rough ER

Does smooth ER have ribosomes attached?

NO

What is the main functions of the smooth ER?

Lipid synthesis and intracellular calcium store for signaling pathways

What cells have larger smooth ER’s? examples?

Cells specialized in lipid metabolism, detoxification or rapid calcium handling (liver, muscle, adrenal glands)

Describe golgi apparatus?

Collection of flattened membrane enclosed cisternae

What is the main function of the Golgi?

Process proteins and lipids it receives from the ER

What are the 3 processing functions of the golgi?

-Modifies by adding or changing chemical groups to proteins

-Sorts where lipids and proteins should go

-Package lipids and proteins into vesicles

How does golgi receive lipids and proteins from ER?

Small vesicles pinch off from ER and fuse with golgi

What does golgi processing form?

lysosomes, peroxisomes and all the secretory vesicles

What is function of lysosome?

Main site of intracellular dgestion

Describe lysosome

A vesicular organelle full of hydrolases and other digestive enzymes that break down damaged cellular structures, food particles ingested by cells and unwanted matter

How many digestive enzymes in lysosomes?

200 enzymes, 60 of which are hydrolases

What are hydrolases subdivided into? How?

Lipases, proteases, phospatases, glucosidases, nucleases and sulfatases (based on what substrate they act upon)

How does peroxisome differ from lysosome?

Has different origin and function

How are peroxisomes formed?

From smooth ER or by self-replication

What do peroxisomes contain?

At least 50 different enzymes (mainly oxidases and catalase)

What does oxidase do?

Combine o2 with hydrogen ions to for H2O2

Why do peroxisome carry catalase?

To decompose the potentially harmful H2O2 formed by oxidases

What do most mammals have in peroxisome?

A crystalline core made from crystalized oxidases

Which mammals dont have a crystalline core in their peroxisomes?

primates

What are 3 functions of peroxisomes?

-Break down fatty acids through beta oxidation

-Detoxify harmful substances

-Lipid biosynthesis

What is the main difference between lysosomes and peroxisomes?

Peroxisomes focus on oxidation reactions while lysosomes focus on hydrolysis

What is mitochondrion? Function?

The powerhouse of the cell that burns food molecules to produce ATP by oxidative phosphorylation

Are mitochondrion self replicative?

YES

Tissues that need more energy have more ___?

mitochondria

What is a vacuole?

A small membrane bound sac within cytoplasam

Function of vacuoles?

Temporary storage of nutrients or waste products

What do vacuoles participate in?

Endocytosis and exocytosis

Can vacuoles fuse with lysosomes? Why would they if yes?

Yes can fuse

-for digestion of vacuole contents

What is cytoskeleton?

Network of fibrillar proteins organized into filaments or tubules

What are the 3 types of cytoskeleton?

-Microtubules

-Microfilaments

-Intermediate filaments

What are 5 functions of cytoskeleton?

-Cell shape (keep or change shape)

-Cell division (spindle fibers)

-Movement (ameboid, ciliary or flagellar)

-Mechanical strength

-Track line system to move molecules/organelles/vesicles within cell

What is the cell membrane composed almost entirely of?

Lipids and proteins

What 3 lipids are in cell membrane?

-Phospholipids

-Sphingolipids

-Cholesterol

What is function of cholesterol in cell membrane?

control fluidity and permeability

Where are sphingolipids found in higher quantities?

nerve cells

What are most abundant lipid in cell membrane?

Phospholipids

What is cell membrane impermeable to?

Water soluble substances

What does the outer surface of cell membrane contain?

Carbohydrates in combonation with lipids and proteins (glycolipids and glycoproteins)