Chapter 3 - Cells Flashcards
Main cellular components:
Plasma membrane
Cytoplasm
Nucleus
Plasma membrane is:
A flexible outer covering of a cell, separating the inside and outside environment of a cell which plays a key role in communicating among cells and acts as a barrier
The plasma membrane consists mostly of:
Lipids and proteins
The lipid layer is made up of
3 types of lipid molecules:
Phospholipids
Cholesterol
Glycolipids
2 types of proteins in the plasma membrane:
Integral proteins - extend into or through the lipid bilayer
Peripheral proteins - loosly attached to the external or internal surface of the membrane
Glycoproteins are
Peripherial proteins
The plasma membrane has ________ permeability
Selective
What is the plasma membrane permeable and not permeable to?
Permeable to water, fatty acids, fat soluable vitamins, steroid, oxygen, and Carbon dioxide
Not permeable to ions, glucose, and AAs
Some integral proteins from iron channels through which …
Potassium ions can move into and out of the cell
Carriers (transporters) do what
Change shape as they move a substance from one side of the membrane to the other
What is unable to pass through the plasma membrane within the vesicles?
Proteins
integral proteins are called what?
What do they recognize?
Called receptors
Recognize and bind a specific molecule
Enzymes do what
Speed up specific chemical rxns
What are cell identity markers and what do they do?
Membrane glycoproteins and glycolipids
They recognize and respond to potentially dangerous foreign cells
Intracellular fluid (ICF)
The cytosol o fa cell, inside the body cell, 2/3rd of body fluid
Extracellular fluid (ECF)
Outside the body cell
Interstitial fluid
In themicroscopic spaces between the cell of tissues
Plasma
Extracellular fluid in blood vessels
Lymph
Extracellular fluid in the lymphatic vessels
Cerebrospinal fluid (CSF)
Extracellular within and around the brain and spinal cord
Materials disolved in body fluids is called
A solute
Solvent
The fluid in which it is dissolved (water)
Concentration
The amt of solute in a soln
Concentration gradient
The difference in concentration between two different areas, the intracellular and extracellular fluid
Substances move across cellular membranes by two processes:
Passive process
Active process
Passive process
A substance moves down its concentration gradient through the membrane using only kinetic energy
Ex: diffusion and osmosis
Active process:
Cellular energy is in the form of ATP is used to push the substance through the membrane
Two types of diffusion:
Simple and facilitated
Simple diffusion:
Substances diffuse across a membrane through the lipid bilayer
Ex: exchange of oxygen and carbon dioxide between the blood and body cells, between blood and air within lungs during breathing, transport method for absorption of lipid, and release of wastes from body cells
Facilitated diffusion is when
Some substances cannot move through simple diffusion and involves ion channels when ions move down their concentration gradients across the lipid bilayer
Ion Channels:
- potassium ions
- chloride ions
- sodium ions
- calcium ions
Substances that need carriers:
1) glucose
2) fructose
3) galactose
4) some vitamins
Osmosis is
A passive process in which water moves from an area of higher water to an area of lower water concentration
Osmotic pressure is when
A soln containing solute particles that cannot pass through a membrane and that exerts pressure on the membrane
Isotonic soln
Cells maintain their nml shape and volume and the conc of solutes are the same on both sides
Hypotonic soln
Lower conc of solutes
Hypertonic soln
Higher conc of solutes
Hemolysis
Rupture of the red blood cells
Crenation
Shrinkage of red blood cells
Energy derived from splitting ATP changes the shape of a carrier protein and now it is called a
Pump
A pump moves a substance when?
It needs to go against its concentration gradient
All cells have thousands of sodium potassium pumps in their plasma membranes which is what?
The most important active transport that expels sodium ions from cells and brings in potassium ions.
A vesicle is
A small rounded sac that transports substances from one structure to another, takes in extracellular fluid, and releases substances into the extracellular fluid
Two main types of transport in vesicles are called:
Endocytosis - move into a cell
- phagocytosis and pinocytosis
Exocytosis - move out of a cell
- sensory cells and nerve cells
Phagocytosis
Cell eating
Pseudopods reach out and grab the large molecule, then the pods fuse to form a phagosome and that enters into the cell.
Residula body
Undigested material remain indefinitely in a vesicle
Phagocytosis occurs only in
Phagocytes
White blood cells and macrophages
Protects the body from dz
Pinocytosis
Cell drinking
Where cells take up tiny droplets of extracellular fluid
Exocytosis results in
Secretion
Secretory cells
Nerve cells - nerotransmitters
Cytoplasm consists of
All the cellular contents, both cytosol and organelles
Cytosol is the site of
Many chemical rxns
The liquid portion of the cytoplasm accounts for what % of the total cell volume?
55%
Cytoskeleton
A network of three different protein filaments extending through the cytosol
1) microfilaments
2) intermediate filaments
3) microtubules
Microfilaments are
The thinnest elements of the cytoskeleton
They contribute to the strength and shape of the cell
Movement, anchor, muscle contractions for locomotion and divisions
Microvilli are
Fingerlike projections that increase the surface area of the cell
Intermediate filaments are
Thicker than microfilaments
Thinner than microtubules
Found in parts of the cells subject to tension (stretching)
Helps hold organelles such as nucleus in place
Microtubules are
The largest of the cytoskeletal components
Long, hollow tubes
Help determine shape/function, migration of chromosomes, movements of cilia and flagella
Organelles are
Specialized structures inside cells that has its own unique set of enzymes that have characteristic shapes and specific functions
Centrosome is located where
Near the nucleus
Has its own pair of centrioles and pericentriolar material
Centrioles are
Two cylindrical structures with:
9 clusters of 3 microtubules (triplet) arranged in a circlular pattern
Surrounding centrioles are ring shaped proteins called tubulins
Role of a tubulin
Organizing center for growth of mitotic spindle
Plays a critical role in Cell division
Cilia and flagella are
The motile projections of the cell surface formed from microtubules
Cilia are numerous and short. They propell fluids across the surfaces of cells (respiratory tract)
Flagella are much longer and usually move the entire cell (sperm cell)
Ribosomes are
Function: protein synthesis
High content of RNA
Contain ribosomal proteins
Large and small subunits
Attached to outer surface of the nuclear membrane and endoplasmic reticulum
Located w/in the mitochondria
Endoplasmic reticulum (ER) is a…
Network of folded membranes in the form of flattened sacs or tubules that extend throughout the cytoplasm
Rough ER
Smooth ER
Rough ER
Extends from the nuclear envelope and appears rough because its studded with ribosomes
Function: synthesize secretory proteins, membrane molecules, glycoproteins, and phospholipids
Smooth ER:
Extends from the Rough ER to form a network of membraneous tubules (lacks ribosomes - smooth)
What are synthesized in the smooth ER
Fatty acids and steroids
Enzymes of the smooth ER in liver cells do what
Release glucose into blood stream and inactivate/detoxify drugs
Enzymes of the smooth ER in muscle cells do what
Release calcium ions for muscle contraction w/ the help of sarcoplasmic reticulum
Golgi complex are
More extensive in cells that secrete proteins
First step in the transport pathway
Consists of 3-20 cisterns
Function: modify and package proteins
What is it called when proteins are discharged from the cell
Exocytosis
Lysosomes
Membrane-enclosed vesicles that contain as many as 60 different digestive enzymes
Function: recycle wornout organelles (autophagy)
Destroy entire cells (autolysis)
Lysosomal membrane contains
Carrier proteins that allow the final products of digestion
Peroxisomes are
Smaller units abundant in the liver where detoxification of harmful substances takes place
Contain catalase that decompose H2O2
Function: Protects other parts of the cell from toxic effects
Proteasomes are
Tiny barrel shaped structures found in both the cytosol and nucleus containing enzymes.
Function: continuous destruction of unneeded/damaged, or faulty proteins
Mitochondria are
The powerhouse of the cell
Site of ATP production
Liver and kidneys
Outer membrane smooth
Inner membrane series of folds called mitochondrial crista
Function: degrades damaged proteins by cutting them into small peptides
What part of the mitochondria contains enzymes?
Mitochondrial matrix
Nucleus is
The largest organelle of the cell
Control center of the cell
Mature RBC have no nucleus
Skeletal muscle cells have a nucleus
Nuclear envelope is
A dbl membrane that separates the nucleus from the cytoplasm
Continuous with the rough ER
Nuclear pores are
Many openings that pierce the nuclear envelope
Control mmt of substance between the nucleus and cytoplasm
Nucleoli are
One or more spherical bodies inside the nucleus
Muscle and liver cells have prominent nucleoli
Genes are
Most of the hereditary units of a cell found within the nucleus
Control cellular structure and direct cellular activities
Nuclear genes are arranged along
Chromosomes
Human body cells (somatic) have how many chromosomes?
46
23 from each parent
In a cell that is not dividing the 46 chromosomes appear as a diffuse granular mass which is called …
Chromatin
The total genetic info carried in a cell or organism is called its
Genome
Whats the DNAs job in genes
Instruction for making proteins
What must happen to DNA to synthesize a protein?
It must be transcribed (copied) to form RNA
What happens to cells when they become damaged/diseased/worn out
Replaced by cell division
2 types:
Reproductive and somatic
Somatic cell division occurs where
In all body cells except the gamets
In what sequences does a cell divide in somatic cell division?
Replication (duplication) of the DNA that make up genes and chromosomes so that the same genetic material can be passed on to newly formed cells
Somatic cell division replaces what?
Dead or injured cells and adds new ones for tissue growth
Ex: skin cells are continually replaced by somatic cell divisions
Reproductive cell division or meiosis is
The process that produces gametes (sperm and oocytes) that the cell needs to form the next generation of sexually reproducing organisms
Cell cycle is the
Sequence of changes that a cell undergoes from the time it forms until it duplicates its contents and divides into two cells
In somatic cells, the cell cycle consists of two major periods, what are they?
Interphase - when a cell is not dividing
Mitosis - when a cell is dividing
Interphase is the phase in which a cell does what
Copies its DNA in preparation for mitosis
Mitosis consists of what two things
Karyokinesis - division of the nucleus
Cytokinesis - division of the cytoplasm into two cells
what does chromatin do
Condenses into chromosomes
Nuclear division is the
Replication and distribution of 2 sets of chromosomes into separate and equal nuclei
Mitosis consists of what 4 phases
Prophase, metaphase, anaphase, telophase
Prop Met Ana over the Telophone
What happens during early prophase
The chromatin fibers condense and shorten into chromosomes
Each chromosomes consist of double stranded chromatids
A constricted region of the chromosome is called the centromere - holds the chromatid pair together
Late prophase
The pericentriolar material of 2 centrosomes starts to form the mitotic spindle
Microtubles lengthen pushing centrosomes to opposite poles (ends) of the cell
Spindle extends from pole to pole and nucleolus and nuclear envelope break down
Metaphase
The centromeres of the chromatid pair are aligned along the microtubules of the mitotic spindle at the center of the mitotic spindle
Midpoint is called the metaphase plate
Anaphase
Centromeres split separating the two chromatids and move them to opposite ends of the cell
Separated chromatids are called chromosomes
Telophase begins when
After chromosomal movement stops
Cytokinesis is
The division of a cells cytoplasm and organelles
Begins late anaphase w/ the formation of a cleavage furrow in the plasma membrane
Microfilaments in the cleavage furrow pull the plasma membrane inward constricting the center of the cell
Cellular diversity means that the human body is comprised of trillions of cells that vary in size and shape and are measured how
In units called micrometers
1 micrometer = 1 one-millionth of a meter
The largest cell is called
A single oocyte - barely visible to the unaided eye
Shapes of cells are related to their
Function
Sperm cell shape
Long tail (flagellum) uses it for locomotion
RBC shape
Disc shape w/ lg surface area that enhances its ability to pass oxygen to other cells
Smooth muscle cells shape
Long spindle shape shortens as it contracts and changes shape to allow the passage for blood flowing through vessels
Microvilli shape
Epithelial cells that line the small intestine provide a lg surface area that speeds up the absorption of digested food
Nerve cells shape
Long extensions that permit them to conduct nerve impulses over great distances
What is aging?
A nml process accompanied by a progressive alteration of the body’s homeostatic adaptive responses
Aging produces what
Observable changes in structure and function and increases vulnerability to environmental stress and dz
Geriatrics is what
The specialized branch of medicine that deals with the medical problems of elderly persons
Gerontology is the
Scientific study of the process and problems associated with aging
What are specific DNA sequences found only at the tips of chromosomes that has to do with aging
Telomeres
They shorten w/ each cell division over time
Eventually they are completely gone which leads to aging and death of cells
Glucose
Most abundant sugar in the body
Plays a role in the aging process
Autoimmune response might be caused by
The changes in certain plasma membrane of glycoproteins and glycolipids that cause antibodies to attach the cell for destruction
Known signs of aging
Wrinkled skin, stiff jnts, hardened arteries
