Cells Flashcards
the cell
the basic structural and functional unit of living organisms.
biochemical activities of cells are determined and made possible by
…. subcellular structures (organelles)
generalized eukaryotic cells - 3 main parts?
plasma membrane (plasmalemma)
cytoplasm
nucleus
plasma membrane
selectively permeable barrier
cellular communication
Each chromosome consists of
a single molecule of DNA and associated packaging proteins
“A phospholipid bilayer with associated integral and peripheral proteins.”
Plasma membrane
Fluid Mosaic Model
arrangement of molecules within the plasma membrane
lipids are barriers
molecules within the membrane I.e. proteins are “gatekeepers”
self-sealing if torn or punctured due to
fluidity
fluid membrane allows cell movement, growth, division, etc through this property
fluidity
plasma membrane allows passage of
lipid-soluble substances
plasma membrane is a barrier to
charged or polar substances
bilayer occurs because lipids are ____
amphipathic, having both polar and non polar parts
The lipid bilayer consists of:
Phospholipids, Cholesterol, and Glycolipids
what mediates membrane fluidity
cholesterol
What makes lipid bilayer less fluid (and stronger) at normal body temperatures ?
cholesterol
What Increases membrane fluidity at lower temperatures?
cholesterol
cholesterol is weakly? due to what
amphipathic… small -OH group
Cholesterol forms ____ bonds with heads of ____ and _____, and fills the space between fatty acid tails
hydrogen;
phospholipids and glycolipids
______ form a lipid bilayer - cholesterol and glycolipids (sugar-lipids) also contribute.
Phospholipids
______ extend into or through the bilayer.
______ span the entire lipid bilayer.
______ attach to the inner or outer surface but do not extend through the membrane.
Integral proteins
Transmembrane proteins (most integral proteins)
Peripheral proteins
______ are membrane proteins with a carbohydrate group attached that protrude into the extracellular fluid.
Glycoproteins
The _____ is the entire “sugary coating” surrounding the membrane
Glycocalyx
The glycocalyx is made up of made up of the carbohydrate portions of the ___ and ____
glycolipids and glycoprotein
two classes of membrane proteins
integral and peripheral
peripheral proteins attach to ___ or ___
phospholipid heads or to integral proteins
protein on one side of the membrane
peripheral
Plasma membrane proteins
ion channels transporters receptors (I.e. ligand) enzymes cell-identity markers
6 different membrane proteins (ICRELC)
▪ Ion channels ▪ Carriers ▪ Receptors ▪ Enzymes ▪ Linkers ▪ Cell identity markers
allows specific ions to move through water-filled pore
Ion Channel (integral)
carries specific substances across membrane by changing shape (I.e. amino acids)
Carrier (integral) also known as the “TRANSPORTERS”
also known as the “transporters”
carrier membrane protein
Recognizes specific ligand and alters cell’s function ins some way (I.e. ADH in kidneys changes permeability of plasma membranes)
Receptor (integral)
Catalyzes reaction inside or outside cell (depending on which direction the active site faces). I.e. lactase splitting disaccharide
Enzyme (integral and peripheral)
Anchors filaments inside and outside the plasma membrane, providing structural stability and shape fo the cell. May also help with MOVEMENT or LINKING cells together
Linker (integral and peripheral)
Distinguishes your cells from anyone else’s (unless identical twins) I.e. Major Histocompatibility (MHC) proteins
Cell-Identity Marker (glycoprotein)
Cell-Identity marker think….
glycoprotein and MHC
sugars attached to proteins or lipids on the outer face of the plasma membrane
glycocalyx
glycocalyx may change continuously… often seen in?
cancer
Rule of Thumb: small, neutrally-charged, lipid-double substances can….? (special case?)
Easily or Freely pass the membrane (water is special case)
Water (unique) and gases
Small, fat-soluble molecules
charged ions (K+,Na+, Ca++, HPO4-, etc)
large, water-soluble molecules (e.g. proteins)
pass easily
pass fairly easily
don’t pass
the lipid bilayer is permeable to nonpolar, uncharged molecules such as __, ___, and ____
oxygen, carbon dioxide, and steroids
the lipid bilayer impermeable to ions and large uncharged
polar molecules such as _____
glucose
the lipid bilayer slightly permeable to small uncharged polar molecules such as ___ and ____
water and urea
Substances that are nonpolar and lipid soluble move into and out of the cell by _____ _____ through the plasmalemma. These include:
COAFF
simple diffusion; COAFF – Oxygen – Carbon dioxide – Fats – Alcohol – Fat-soluble vitamins (A, D, E, and K)
Some polar substances can diffuse across the plasma membrane because they are small enough:
water and urea
Most water soluble particles are not able to diffuse
through the lipid bilayer because they are repelled by the ?
nonpolar hydrocarbon chains
Due to its hydrophobic interior, the plasma membrane is a physical barrier to unhindered diffusion, but molecules will passively diffuse if they are…
– Lipid soluble, or
– Small enough to pass through the membrane pores, or
– Assisted by carrier molecules
concentration gradient
chemical
electrical gradient
charges (electrical)
electrochemical gradient
chemical and electrical charges
Oxygen molecules and sodium ions are more concentrated in the
ECF or extracellular fluid
Carbon dioxide and potassium ions are more concentrated in the
cytosol
Passive processes of movement = ?
ex’s?
no energy expenditure required
– Diffusion
• Simple diffusion
• Osmosis
• Facilitated diffusion
– FiltrationActive processes of movement require?
ex’s?
(energy expenditure required)
– Active transport
• Primary active transport
• Secondary active transport
– Bulk transport (vesicular transport)
• Exocytosis • Endocytosis • Transcytosis
is the passive spread of particles through random motion, from areas of high concentration to areas of low concentration.
diffusion
Diffusion is affected by:
– the amount of substance and the steepness of the concentration gradient.
– Temperature
– Surface area
– Diffusion distance
Osmosis
▪Diffusion of solvent (water) through a semipermeable membrane
Osmosis follows the rules of diffusion:
▪Follows the rules of diffusion:
– Requires a concentration gradient
– Movement is from a compartment with a higher water concentration (lower solute concentration) to an area of lower water concentration (higher solute concentration)
▪Requirements:
– Semipermeable membrane
– At least one “osmotically active” solute, i.e., one that is in higher concentration on one side and can’t pass through the membrane
▪Osmotic pressure
tonicity of a solution is described relative to the tonicity of the…
intracellular fluid (cytosol) of the cell(s) involved
Some molecules that the cell requires are too polar to diffuse through the lipid bilayer, or, like glucose, are too large to pass through membrane pores so they:
solute binds to protein carrier on one side of the membrane and is released on the other side after the transporter undergoes a change in shape (FACILITATED DIFFUSION)
water soluble vitamins cannot pass
cytoplasmic membrane
Solutes that move by ___ ____ include glucose, fructose, galactose, and some vitamins
facilitated diffusion
Foot stomp: In _____, the energy is derived directly from the breakdown of ATP. In the _____, the energy is derived secondarily from energy that has been stored in the form of ionic concentration differences between the two sides of a membrane.
primary active transport
secondary active transport
sodium-potassium pump is a form of?
primary active transport (against the weird K - concentration gradient)
In _____, the energy stored in a Na+ or H+ concentration gradient is used to drive other substances across the membrane against their concentration gradient
secondary active transport
The Na+ or H+ concentration gradient was established by primary active transport, so secondary active transport indirectly uses energy obtained from _____?
the hydrolysis of ATP.
carry two substances across the membrane in
opposite directions.
Antiporters
carry two substances across the membrane in the
same direction.
Symporters
examples of antiporters
Sodium and calcium, or sodium and hydrogen
examples of symporters
sodium and glucose or sodium and amino acid
symporters and antiporters use ___ active transport
secondary
three types of endocytosis?
– receptor-mediated endocytosis
– Phagocytosis
– bulk-phase endocytosis (pinocytosis)
bulk transport or vesicular transport is ___ transport
active (uses energy)
highly selective endocytosis, cells take up specific ligands
receptor mediated endocytosis
bulk phase endocytosis
pinocytosis or cell drinking (invaginating with a “sip” of ECF)
pinocytosis
bulk phase or cell drinking
phagosome + lysosome =
phagocytosis
clathrin with endosome to lysosome =
receptor mediated endocytosis
lysosome + vesicle with dissolved solutes
pinocytosis
exocytosis examples
– secretory cells that produce substances such as digestive enzymes, hormones, mucus, etc.
– nerve cells, which release neurotransmitters
transcytosis
Most often occurs across endothelial cells lining blood vessels wherein materials are moved between the blood plasma and interstitial fluid
2 components of cytoplasm
cytosol and organelles
the site of chemical reactions, energy release from them, etc
cytosol
spherical body that produces ribosomes
Nucleolus
a double membrane that separates the nucleus from the cytoplasm
Nuclear envelope
look at image on slide 60
good work
a blob of ribosomal RNA
Nucleolus
produces both ribosomal subunits
Nucleolus
produces both ribosomal subunits
Nucleolus
▪A dense complex of RNA, DNA, and protein
▪Forms around the portions of certain chromosomes having regions that code for production of ribosomes
▪Produces both ribosomal subunits.
▪Catch phrase is “blob of ribosomal RNA”
Nucleolus
▪A complex of DNA and proteins
▪represents the relaxed, uncoiled chromosomes of the interphase nucleus
Chromatin
site of protein synthesis
ribosomes
where amino acids are assembled into proteins (on what)
ribosomes
small and large subunit, either free or attached
ribosomes
both ribosomal subunits are manufactured in the….
nucleolus
reside, disassembled, in the cytoplasm until needed
ribosomal subunits
Subunit which initiates translation, recruits the large ribosomal subunit, and reads the mRNA
The small subunit
subunit which joins the amino acids to form a polypeptide chain
The large subunit
ER which is more linear
Rough endoplasmic reticulum (RER)
ER which is a network of tubules
smooth endoplasmic reticulum (SER)
A stack of 3-20 flattened, membrane- enclosed sacs called cisternae
Golgi Complex
Golgi
– Transport vesicles arriving from the rough ER fuse with the ___ face of the Golgi
– Secretory vesicles, lysosomes, and peroxisomes bud from the ___ face
cis
trans
Golgi complex functions
receive “immature” proteins form rough ER
synthesize carbohydrate
“packing and export mechanism for the cell”
▪“The powerhouses of the cell”
▪Have two membranes, outer and inner; the inner folds in many times producing cristae
▪Self-replicating—have their own DNA. Used to establish heredity-only from mother
▪Contain enzymes responsible for cellular respiration and the Krebs cycle
▪Most of the cell’s ATP is produced here (cellular respiration)
Mitochondria
mitochondria are about the size of ____ and have their own _____
bacteria; ribosomes
Lysosomes are where? contain?
vesicles that form from the Golgi complex and contain powerful digestive enzymes
vesicles that form from the Golgi complex and contain powerful digestive enzymes
Lysosomes
carry out autophagy (digest old organelles)
carry out autolysis (digest entire cell)
lysosomes
▪Another Golgi complex product ▪Detoxify several toxic substances such as alcohol
▪Abundant in the liver
▪Also break down hydrogen peroxide (H2O2), a byproduct of oxidation, using the enzyme catalase
▪New peroxisomes form from pre-existing ones by enlarging and dividing, so they are self- replicating (but they do not have DNA)
Peroxisomes
▪Continuously degrade(destroy) unneeded, damaged, or faulty proteins
▪Found in the cytosol and the nucleus ▪Some diseases may result from failure of proteasomes to function properly, such as the abnormal proteins that accumulate in brain cells of persons with Parkinson disease and Alzheimer disease
Proteasomes (can change shape)
▪Membranous sacs within the cytoplasm of cells
▪Commonly formed when part of the plasma membrane folds inward and pinches off during phagocytosis
▪May be associated with lysosomes, forming a digestive vacuole
▪May be for temporary storage of material
Vacuoles
▪Located near the nucleus
▪Centrioles: paired, perpendicular cylinders
▪Each cylinder composed of 9 microtubule triplets
▪Function: assembly of microtubules
Centrosome
the microtubule organizing center
centrosome
▪Non-living components within cells ▪Not bounded by membrane ▪Most common – Glycogen – Lipids – Pigments – Crystals
inclusions
A cancerous neoplasm (tumor) that tends to metastasize
Malignancy
Malignant tumors that arise from epithelial cells.
Carcinoma
A general term for any cancer arising from muscle cells or connective tissues.
Sarcoma
Alteration in the size, shape,
and organization of cells due to chronic
irritation or inflammation; may progress to
neoplasia if the conditions persist, or revert
to normal if the irritation is removed.
Dysplasia
An increase in the number of cells of a tissue due to an increase in the frequency of cell division.
Hyperplasia
Metaplasia
The transformation of one cell type into another.
-plasia:
“growth, cellular multiplication,”
A substance introduced into circulation by tumor cells that indicates the presence of a tumor, as well as it’s specific type; may be used to screen, diagnose, and evaluate a response to treatment, and monitor for recurrence of the cancer.
Tumor marker
functions of lysosomes
digest -endocytosis
transport digestion into cytosol
autophagy
autolysis
