Homeostasis and Cells Flashcards
All cells arise from _______________ in which one cell divides into _______________
existing cells; two identical cells
The average adult human body consists of more
than
100 trillion cells
are the basic, living, structural, and functional units of the body
Cells
The scientific study of cells is called
cell biology or cytology
-first lenses used in Europe
-used to determine cloth quality (weave and precision)
-combos of lenses gave better view
Late 1500’s
Leeuwenhoek uses microscope to study nature
Early 1600’s
uses microscope to study nature
Leeuwenhoek
first to view pond water organisms
Leeuwenhoek
First to see living microscopic organisms
Leeuwenhoek
*Leeuwenhoek
*first to view pond water
organisms
*First to see living
Microscopic organisms
*Made careful sketches
Early 1600’s
Anton van Leeuwenhoek in _____________
- Used a handmade microscope to observe pond
scum & discovered single-celled organisms
1673
Used a handmade microscope to observe pond scum & discovered single-celled organisms
Anton van Leeuwenhoek
Anton van Leeuwenhoek in 1673 used a handmade microscope to observe pond scum & ______________________________
discovered single-celled organisms
Anton van Leeuwenhoek used a handmade microscope to observe pond scum & discovered single-celled organisms and called them
animalcules
*He also observed blood cells from fish, birds, frogs, dogs, and humans
* Therefore, it was known that cells are found in animals as well as plants
Anton van Leeuwenhoek
Used light microscope to look at thin slices of plant tissues – cork
Robert Hooke ( 1665)
Looked empty, like monk’s chamber
Called tiny chambers
cells
*German Botanist (plants)
*All plants looked at were made of cells, so concluded:
*“All plants are made of cells.”
Matthias Schleiden 1838
- German scientist who studied animals – zoologist
*Saw that all animals he studied were cellular so concluded:
*“All animals are made of cells.”
Theodore Schwann – 1839
*German physician who studied cell reproduction
*“Where a cell exists, there must have been a preexisting cell…..”
Rudolf Virchow – 1855
Discovery of cell (Timeline)
*Robert Hooke (mid-1600s) : CELL
*Robert Brown (1831) : NUCLEUS
*Johannes Purkinje (1830s) : PROTOPLASM
*Theodor Schwann & Matthias Schleiden (1839)
*Rudolf Virchow (1855)
The Cell Theory
- All living things are composed of cells
- Cells are the basic units of structure and function in living things
- New cells are produced from existing cells
Parts of a cell 9that can be seen in a compund microscope)
Plasma membrane
Cytoplasm
Nucleus
forms the cell’s flexible outer surface, separating the cell’s internal environment (everything inside the cell) from the
external environment (everything outside the cell).
Plasma membrane
consists of all the cellular contents between the plasma
membrane and the nucleus.
Cytoplasm
Cytoplasm has two components
cytosol and organelles
is a large organelle that houses most of a cell’s DNA.
Nucleus
Within the nucleus, each chromosome, a single molecule of DNA associated with several proteins, contains thousands of hereditary units called _________ that control most
aspects of cellular structure and function.
genes
The plasma membrane, a flexible yet sturdy barrier that
surrounds and contains the cytoplasm of a cell, is best
described by using a structural model called the
fluid mosaic model
is the basic structural framework of the plasma
membrane
Lipid Bilayer
Lipid Bilayer is made up of 3 types of lipid molecules
- 75% - phospholipids (lipids that contain phosphorus)
- 20% - cholesterol (a steroid with an attached -OH (hydroxyl) group)
- 5% - glycolipids (lipids with attached carbohydrate groups)
What is the polar part in phospholipids?
phosphate containing “head,” which is hydrophilic
hydro
water
philic
loving
What are the non-polar part in phospholipids?
2 long fatty acid “tails,” which are hydrophobic hydrocarbon
chains.
Arrangement of Membrane Proteins:
Integral proteins and Peripheral proteins
extend into or through the lipid bilayer and are
firmly embedded in it
Integral proteins
Most integral proteins are _________________, which means that they span the entire lipid bilayer and protrude into both the cytosol and extracellular fluid.
transmembrane proteins
they span the entire lipid bilayer and protrude into both the cytosol and extracellular fluid
transmembrane proteins
are not as firmly embedded in the membrane.
Peripheral proteins
They are attached to the polar heads of membrane lipids or to integral proteins at the inner or outer surface of the membrane.
Peripheral proteins
Many integral proteins are _______________ with carbohydrate groups attached to the ends that protrude into the extracellular fluid.
glycoproteins
proteins with carbohydrate groups attached to the ends that protrude into the extracellular fluid.
glycoproteins
Carbohydrates are ____________________
oligosaccharides
oligo
few
saccharides
sugars
chains of 2 to 60 monosaccharides that may be straight or
branched
carbohydrates/oligosaccharides
The carbohydrate portions of glycolipids and glycoproteins form an extensive sugary coat called the
glycocalyx
The pattern of carbohydrates in the glycocalyx __________________________________________________
varies from one cell to another
Functions of the Plasma Membrane
- Acts as a barrier separating inside and outside of the cell.
- Controls the flow of substances into and out of the cell.
- Helps identify the cell to other cells (e.g., immune cells).
- Participates in intercellular signaling.
are fluid structures because the lipids and many of the proteins are free to rotate and move sideways in their own half of the bilayer.
Membranes
largely reflect the functions a cell can perform.
Membrane proteins
Forms a pore through which a specific ion can flow to get
across membrane. Most plasma membranes include
specific channels for several common ions.
lon channel (integral)
transports a specific substance across membrane by undergoing a change in shape. For example, amino acids, needed to synthesize new proteins, enter the body via carriers
carrier (integral)
Carrier proteins are also known as
transporters
Recognizes specific ligand and alters cell’s function in
some way. For example, antidiuretic hormone binds
to receptors in the kidneys and changes the water permeability of certain plasma membranes
Receptor (integral)
Catalyzes reaction inside or outside cell (depending on
which direction the active site faces). For example lactase protruding from epithelial cells lining your small intestine splits the disaccharide lactose in the milk you drink.
Enzyme (integral and peripheral)
Anchors filaments inside and outside the plasma
membrane, providing structural stability and shape for the cell. May also participate in movement of the cell or link two cells together.
Linker (integral and peripheral)
Distinguishes your cells from anyone else’s (unless you are an identical twin). An important class of such markers are the major histocompatibility (MHC) proteins
Cell identity marker (glycoprotein)
MHC means
major histocompatibility
Membranes are _____________________; that is, most of the membrane lipids and many of the membrane proteins easily rotate and move sideways in their own half of the bilayer
fluid structures
means that a structure permits the passage of substances through it
permeable
means that a structure does not permit the passage of substances through it
impermeable
Membranes are fluid structures; that is, most of the membrane lipids and many of the membrane proteins easily
rotate and move sideways in their own half of the bilayer
of the plasma membrane to different substances
varies.
permeability
Plasma membranes permit some substances to pass more
readily than others. This property of membranes is termed
selective permeability
membrane proteins can be structurized according to:
Structure and Function
For Structure Membrane Proteins (2) :
Integral and Peripheral Proteins
For Function Membrane Proteins (4):
Membrane Transporters
Structural Proteins
Membrane Enzymes
Membrane Receptors
Types of Membrane Transport Proteins
Carrier proteins
Channel proteins
Channel Proteins form
Open Channels and Gated Channels
Types of gated channels
Mechanically gated channel
Voltage-gated channel
Chemically-gated channel
Structural Proteins are found in
Cell junctions and cytoskeleton
Membrane enzymes are active in
metabolism and signal transfer
membrane receptors activate
membrane enzymes
membrane receptors are active in
receptor-mediated endocytosis and signal transfer
membrane receptors open and close
chemically gated channel
embedded in lipid bilayer
Transport Proteins
channel for lipid insoluble molecules and ions to pass freely through
Channel Proteins
bind to a substance and carry it across membrane, change shape in process
Carrier Proteins
create a water-filled pore
channel proteins
open and close in response to signals
gated channels
or pores are usually open
open channels
never form an open channel between the two sides of the membrane
carrier proteins
carrier proteins can be classified as
uniport carriers, symport carriers, antiport carriers
cotransporters
symport carriers and antiport carriers
Substance Permeability Across Membrane
Few molecules move freely: Water, Carbon dioxide, Ammonia, Oxygen
uses energy of molecular motion. does not require ATP
Diffusion
Requires energy from ATP
primary and secondary active transport, endocytosis, exocytosis, phagocytosis
2 types of diffusion
simple diffusion and facilitated diffusion
primary active transport creates concentration gradient for
secondary active transport
uses a membrane-bound vesicle
endocytosis, exocytosis, phagocytosis
mediated transport requires a membrane protein
secondary active transport
molecules goes through lipid bilayer
simple diffusion
a substance moves down its concentration or electrical gradient to cross the membrane using only its own kinetic energy (energy of motion).
Passive processes
Types of Passive Transport
- Diffusion
- Osmosis
- Facilitated diffusion
molecules move to equalize concentration
Diffusion
- Special form of diffusion; Fluid flows from lower solute concentration to higher solute concentration
- Often involves movement of water: Into cell/Out of cell
Osmosis
solvent + solute =
solution
– Solutes in cell more than outside
– Outside solvent will flow into cell
Hypotonic
– Solutes equal inside & out of cell
Isotonic
– Solutes greater outside cell
– Fluid will flow out of cell
Hypertonic
is a specific type of diffusion; it is the passage of water from a region of high water concentration through a semi permeable membrane to a region of low water concentration.
Osmosis
- Channels (are specific) help molecule or ions enter or leave the cell
- Channels usually are transport proteins (aquaporins facilitate the movement of water)
- No energy is used
Facilitated Diffusion
How Facilitated Diffusion works
- Protein binds with molecule
- Shape of protein changes
- Molecule moves across membrane
movement of water and solute molecules across the cell membrane due to hydrostatic pressure generated by the cardiovascular system
Filtration
Molecular movement requires energy (against gradient)
Active Transport
Example of active transport is
sodium-potassium pump
process of sodium-potassium pump
The sodium-potassium pump system moves sodium and potassium ions against large concentration gradients. It moves two potassium ions into the cell where potassium levels are high, and pumps three sodium ions out of the cell and into the extracellular fluid.
Three sodium ions bind with the protein pump inside the cell. The carrier protein then gets energy from ATP and changes shape. In doing so, it pumps the three sodium ions out of the cell. At that point, two potassium ions from outside the cell bind to the protein pump. The potassium ions are then transported into the cell, and the process repeats. The sodium-potassium pump is found in the plasma membrane of almost every human cell and is common to all cellular life. It helps maintain cell potential and regulates cellular volume.
Movement of Phagocytosis is
To the ICF
Vesicles of Phagocytosis is
Large membrane bound vesicle
Function of Phagocytosis is
engulfs a bacterium or other particle
Mechanism of Phagocytosis is
phagosome pinches off from the cell membrane
Movement of Endocytosis is
To the ICF
Vesicles of Endocytosis is
Smaller vesicles
Function of Endocytosis is
To move large molecules or particles into cells
Mechanism of Endocytosis is
membrane surface indents, could be nonselective or receptor mediated
Movement of Exocytosis is
To the ECF
Vesicles of Exocytosis is
Intracellular vesicles
Function of Exocytosis is
export large lipophobic molecules, (proteins), get rid of wastes left in lysosomes, insert proteins into the cell membrane
Mechanism of Exocytosis is
Rabs, help vesicles dock onto the membrane, & SNAREs, which facilitate membrane fusion
- Movement of large material
- Particles
- Organisms
- Large molecules - Movement is into cells
Endocytosis
Types of endocytosis
- bulk-phase (nonspecific)
- receptor-mediated (specific)
Process of Endocytosis
- Plasma membrane surrounds material
- Edges of membrane meet
- Membranes fuse to form vesicle
Forms of Endocytosis
Phagocytosis and Pinocytosis
cell eating
Phagocytosis
cell drinking
Pinocytosis
- Reverse of endocytosis
- Cell discharges material
Exocytosis
Process of Exocytosis
- Vesicle moves to cell surface
- Membrane of vesicle fuses
- Materials expelled
What are the 3 parts of the cell that can be seen under a compound microscope?
Nucleus, Plasma Membrane, Cytoplasm
all the cellular contents within the plasma membrane except for the nucleus—consists of
cytosol and organelles
—all the cellular contents within the plasma membrane except for the nucleus—consists of cytosol and organelles.
Cytoplasm
is the fluid portion of cytoplasm, containing water, ions, glucose, amino acids, fatty acids, proteins, lipids, ATP, and waste products
Cytosol
It is the site of many chemical reactions required for a cell’s existence
Cytosol
are specialized structures with characteristic shapes that have specific functions
Organelles
- is a network of protein filaments that extends throughout the cytosol
Cytoskeleton
are the thinnest elements of the cytoskeleton
Microfilaments
proteins in microfilament
actin and myosin
They help generate movement and provide mechanical support.
Microfilaments
are thicker than microfilaments but thinner than microtubules
Intermediate filaments
the largest of the cytoskeletal components, are long, unbranched hollow tubes composed mainly of the
protein tubulin.
Microtubules
The assembly of microtubules begins in an organelle called the
centrosome
Function of Cytoskeleton
- Serves as a scaffold that helps determine a cell’s shape
and organize the cellular contents. - Aids movement of organelles within the cell, of
chromosomes during cell division, and of whole cells such
as phagocytes.
are specialized structures within the cell that have characteristic shapes, and they perform specific functions in cellular growth, maintenance, and reproduction
Organelles
What structure of the cell which has a pair of centrioles and the pericentriolar matrix?
centrosome
microtubule organizing center
Centrosome
Centrosome (microtubule organizing center), is located near the nucleus, consists of two components:
a pair of centrioles and the pericentriolar matrix
Functions of the Centrosomes
- The pericentriolar matrix of the centrosome contains tubulins that build microtubules in nondividing cells.
- The centriols of the centrosome forms the mitotic spindle during cell division.
are cylindrical structures, each composed of nine
clusters of three microtubules (triplets) arranged in a circular pattern
Centrioles
Surrounding the centrioles is the _____________________, which contains hundreds of ring-shaped complexes composed of the protein tubulin
pericentriolar matrix
forms the mitotic spindle during cell division
centrioles
- are numerous, short, hairlike projections that extend from the surface of the cell
- Each contains 20 microtubules
Cilia
Each is anchored to a basal body just below the surface of the plasma membrane
Cilia
Each cilia is anchored to a _______________ just below the surface of the plasma membrane
basal body
singular of cilia is
cilium
- are similar in structure to cilia but are typically much longer
- Usually move an entire cell
Flagella
Generates forward motion along its axis by rapidly wiggling in a wavelike pattern.
Flagella
It is the only example of a flagellum in the human body
sperm
What is the functional difference between cilia and flagella?
The motion of cilia is rotational, very fast moving. The motion of flagella is rotary movement in prokaryotes whereas it is bending movement in eukaryotes.
The site of protein synthesis is?
Ribosomes
The name of these tiny structures (ribosomes) reflects their high content of one type of ribonucleic acid (ribosomal RNA, or rRNA), but each ribosome also includes more than
50 proteins
Structurally, a ribosome consists of two subunits, one about half the size of the other. What are these subunits?
large and small subunits
Where are subunits of ribosomes synthesized and assembled?
nucleolus
is a network of membranes in the form of flattened sacs or tubules
Endoplasmic Reticulum
is continuous with the nuclear membrane and is usually folded into flattened sacs.
Rough ER
In some cases, enzymes attach the proteins to carbohydrates to form
glycoproteins
In other cases, enzymes attach the proteins to phospholipids, also synthesized by
rough ER
These molecules may be incorporated into the membranes of organelles, inserted into the plasma membrane, or secreted via exocytosis.
glycoproteins and phospholipids
produces secretory proteins, membrane proteins, and many organellar proteins
rough ER
extends from the rough ER to form a network of membrane tubules
Smooth ER
does not have ribosomes on the outer surfaces of its membrane
Smooth ER
contains unique enzymes that make it functionally more diverse than rough ER
Smooth ER
Because it lacks ribosomes, smooth ER does not synthesize proteins, but it does synthesize ________________________________________, such as estrogens
and testosterone.
fatty acids and steroids
However, smooth ER contains unique enzymes that make it
functionally more diverse than rough ER. Because it lacks
ribosomes, smooth ER does not synthesize proteins, but it
does synthesize fatty acids and steroids, such as
estrogens and testosterone
It consists of 3 to 20 cisterns (sis-TER-nē = cavities; singular is cistern), small, flattened membranous sacs with bulging edge.
- Golgi complex
(cis) face is a cistern that faces the rough ER
Convex entry
(trans)face is a cistern that faces the plasma membrane
Concave exit
Sacs between the entry and exit faces are called
medial cisterns
What are the three general destinations for proteins that leave the Golgi complex?
lysosomes, the plasma membrane, or secretion
Often referred to as the “digestive organelles” of the cell
Lysosomes
are membrane-enclosed vesicles that form from the
Golgi complex
Lysosomes
Contains as many as 60 kinds of powerful digestive and
hydrolytic enzymes that can break down a wide variety of
molecules once lysosomes fuse with vesicles formed during
endocytosis
also help recycle worn-out cell structures
Lysosomal enzymes
The process by which entire worn-out organelles are digested is called
autophagy
The organelle to be digested is enclosed by a membrane derived from the ER to create a vesicle called an
autophagosome
is also involved in cellular differentiation, control of growth, tissue re-modeling, adaptation to adverse environments, and cell defense
autophagy
may also destroy the entire cell that contains them, a process known as autolysis
Lysosomal enzymes
Lysosomal enzymes may also destroy the entire cell that
contains them, a process known as
autolysis.
Another group of organelles similar in structure to lysosomes, but smaller, are the
peroxisomes
Peroxisomes are also called
microbodies
Peroxisomes contain several ___________________, enzymes that can oxidize (remove hydrogen atoms from) various organic substances
oxidases
in peroxisomes oxidize toxic substances, such as alcohol
Enzymes
peroxisomes are very abundant in the _____________, where
detoxification of alcohol and other damaging substances occurs
liver
Mitochondria generate most of the ATP through ____________________
aerobic (oxygen-requiring) respiration
are referred to as the “powerhouses” of the cell
Mitochondria
A cell may have as few as a _____________ or as many as
________________ mitochondria, depending on its
activity.
hundred; several thousand
are usually located within the cell where oxygen enters the cell or where the ATP is used.
Mitochondria
contains a series of folds called mitochondrial cristae
Internal mitochondrial membrane
The Internal mitochondrial membrane contains a series of folds called
mitochondrial cristae
The central fluid-filled cavity of a mitochondrion, enclosed by the internal mitochondrial membrane, is the
mitochondrial matrix
a spherical or oval-shaped structure that usually is the most prominent feature of a cell
nucleus
“Control Center”
nucleus
Within the nucleus are most of the cell’s hereditary units, called _______ which control cellular structure and direct cellular activities
genes
is a long molecule of DNA that is coiled together with several proteins
chromosome
This complex of DNA, proteins, and some RNA is called
chromatin
The total genetic information carried in a cell or an organism is its
genome
Electron micrographs reveal that chromatin has a
beads-on-astring structure
Each bead is a nucleosome that consists of double-stranded DNA wrapped twice around a core of eight proteins called
histone
help organize the coiling and folding of DNA
histone
Just before cell division takes place, however, the DNA replicates (duplicates) and the loops condense even more, forming a pair of
chromatids
forms a pore through which a specific ion can flow to get across membrane
ion channel (integral)
