chapter 3- cells Flashcards
what are cells?
the basic, living, structural, and functional units of the body
The scientific study of cells is called
cell biology or cytology.
plasma membrane
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).
cytoplasm
consists of all the cellular contents between the plasma membrane and the nucleus
what are the two components the cytoplasm contains
cytosol and organelles
cytosol
it is the fluid inside the cytoplasm the gel in which the organelles are anchored in
nucleus
is a large organelle that houses most of a cell’s DNA
chromosome
a single molecule of DNA associated with several proteins
fluid mosaic model
a flexible yet sturdy barrier that surrounds and contains the cytoplasm of a cell, is best described by using a structural model
lipid bilayer
two back-to-back layers made up of three types of lipid molecules—phospholipids, cholesterol, and glycolipids
proteins are
are “gatekeepers” for certain molecules and ions
phospholipids
it’s about 75% of the membrane lipids. lipids that contain phosphorus. looks like a head and tail.
Polar head
hydrophilic head. It likes water
Non-polar tail
Hydrophobic tail. Does not like water
cholesterol
20% of lipids. a steroid with an attached OH (hydroxyl) group
glycolipids
5% of lipids. lipids with attached carbohydrate groups
The bilayer arrangement occurs because the lipids are
amphipathic
amphipathic
molecules, which means that they have both polar and nonpolar parts
Membrane proteins are classified as
integral or peripheral according to whether they are firmly embedded in the membrane
Integral proteins
extend into or through the lipid bilayer and are firmly embedded in it
transmembrane proteins
which is Most integral proteins. means that they span the entire lipid bilayer and protrude into both the cytosol and extracellular fluid
peripheral proteins
are not as firmly embedded in the membrane. They are attached to the polar heads of membrane lipids or to integral proteins at the inner or outer surface of the membrane.
glycoproteins
proteins with carbohydrate groups attached to the ends that extend into the extra cellular fluid
glycocalyx
The carbohydrate portions of glycolipids and glycoproteins form an extensive sugary coat
ion channels
pores or holes that specific ions, such as potassium ions (K+), can flow through to get into or out of the cell. Most ion channels are selective; they allow only a single type of ion to pass through.
a cell is made out of
plasma membrane
cytoplasm
Nucleus
Functions of the membrane protein
channel transporter receptor Cell Identity Marker Linker Act as Enzyme
channel protein (integral)
would be like a hallway that’s always open and molecules can pass through into the cell
Transporter Proteins (integral)
will still be specific to what it brings in, it binds and changes the shape and moves it across the membrane into the cell or out
Receptor Proteins (integral)
bind to substance. will sit on the surface or in the membrane and a specific substance, and will cause a change in the cell.
Cell Identity Marker (glycoprotein)
recognize self vs. non-self
Linker (integral & peripheral)
anchor proteins in cell membrane or to other cells
- cell shape & structure
Act as Enzyme (integral & peripheral)
speed up reactions
molecules moves down the concentration gradient from
High to low because it does not require any energy
why doesn’t molecules want to move from high to low from the concentration gradient
because high to low would require energy
Transport processes
Active and passive transport
Passive transport
move “down” their concentration gradient
-requires No energy
Active transport
move a substance against its [gradient]
-Requires energy (ATP)
types of passive transports
Diffusion of solutes
Osmosis = Diffusion of water
Facilitated diffusion
Diffusion aka Simple Diffusion
Movement of particles from [H] → [L]
“down” or “with” the [ ] gradient
Uses no ATP
Osmosis
The net (overall) movement of H2O across a selectively permeable membrane from [H] → [L] (from lower [] of solutes → higher [] of solutes).
if there is a lot of water in a space means there is less
solutes (Na, K)
for osmosis you can’t have
high and high or low and low
To stop osmosis is an
osmotic pressure
Osmotic Pressure
The amount of pressure that would have to be applied to 1 side of a selectively permeable membrane in order to stop osmosis.
Filtration
The process where fluid & particles are driven through a selectively permeable membrane by Hydrostatic Pressure.
Facilitated Diffusion
A carrier-mediated process
Uses a membrane bound (transmembrane) protein
[H] to [L]
Uses no ATP
Active transport pt.2
A carrier-mediated process
Uses a membrane bound (transmembrane) protein called a pump
[L] to [H] (or even [H] to [L])
Uses ATP
-requires 40% of cellular ATP
Sodium-Potassium Pump
(Na+/K+ ATPase pump)
most common example
all cells have 1000s of them
maintains low concentration of Na+
& a high concentration of K+ inside cell
2 K+ in, 3 Na+ out
operates continually
Vesicular Transport of Particles
Endocytosis and Exocytosis (requires no ATP)
Endocytosis
bringing something into cell
receptor-mediated
binds to receptor on surface
Phagocytosis
- Eating other cells like dead cells or waste, viruses by WBC and macrophages
pinocytosis aka bulk phase endocytosis
- Whatever material that the cell brings in is liquid. basically
cells drinking
Exocytosis
release something from cell
- Vesicles form inside cell, fuse to cell membrane
- Release their contents
- digestive enzymes, hormones, neurotransmitters or waste products
Tonicity
The ability of a solution to affect the fluid volume w/i a cell. If a solute can’t pass through a plasma membrane, but remains more concentrated on 1 side than on the other, it will cause osmosis.
Types of tonicity
Isotonic solution
Hypertonic solution
Hypotonic solution
Isotonic
means the concentration of water is equal or similar to the concentration of the solutes.
Hydrotonic
is when there’s more water than solutes making the cell swell (cause the cell to burst)
aka bursting= lysis
Hypertonic
is when the solutes is greater than the water(shrinks the cell)
aka shrinking=crenation
Nucleus
Large organelle w/ double membrane nuclear envelope. Has it own membrane, it’s important because DNA is stored in the nucleus.
Nucleolus is important and must be protected because it produces ribosomes
Nucleolus
- spherical, dark bodies w/i the nucleus
- site of ribosome production
Chromatin
is the storage form of DNA
If cell is dividing (mitosis) chromatin folds to form
chromosomes
Chromosomes are formed from
sister chromatids
Centrosome
Contains 2 centrioles wh/ form the mitotic spindle seen during mitosis
Centromere binds
2 sister chromatids`
Mitochondria
is the powerhouse of the cell. Site of ATP synthesis when Oxygen is available. It has a inner and outer membrane
Ribosome
Site of protein synthesis
Ribosomal Subunits
- Large + small subunits
- made in nucleolus
- assembled in the cytoplasm
Rough Endoplasmic Reticulum
- Rough ER is covered w/ ribosomes.
- continuous w/ nuclear envelope & contains ribosomes
- Synthesizes & processes proteins
Endoplasmic Reticulum
Network of membranes
Smooth Endoplasmic reticulum
- Has no ribosomes.
- synthesizes fatty acids & steroids (estrogen & testosterone)
- detoxifies harmful substances (alcohol) (many in liver cells)
Golgi Complex
- Proteins made in rough ER go to Golgi
- Golgi complex role is to process, package, & deliver proteins (and lipids) to the plasma membrane & secretory vesicles and lysosomes
Packaging by Golgi Complex
- Proteins pass from rough ER to golgi complex in transport vesicles
- Processed proteins pass from entry to exit in transfer vesicle
- Finished proteins exit golgi as membrane, secretory, or transport vesicle
Lysosomes
Digest enzymes
Peroxisomes
- smaller than lysosomes,
- detoxify toxic substances (ex alcohol) many in liver
- remove H+ atoms
Proteasomes
- destroy unneeded/damaged proteins
- found in cytosol & nucleus
Cilia/Flagella
Hairlike projections, helps the cells movement
Villi/microvilli
absorption
Cytoskeleton
protein network in cytosol
Provides shape and support to cell
DNA (Genes)
contain instructions for making proteins
Protein Synthesis
Transcription = DNA → RNA Translation = RNA → Proteins
The Cell Cycle in Somatic Cells
- Process where cell duplicates its contents & divides in 2.
- 46 chromosomes duplicated so genes are passed to new cells
- interphase
- mitosis
Stages of interphase
G1
S
G2
G1
duplicates organelles & cytosolic components
S
DNA Synthesis (replication)
G2
make enzymes & other proteins for division
Interphase
distinct nucleus
absence of chromosomes
Prophase
- Chromatin forms visible chromosomes
- Nucleolus & nuclear envelope disappear
- Each centrosome moves to oppo ends of cell
Metaphase
Chromatid pairs line up in middle of cell at the metaphase plate
Anaphase
- Chromatids (single-stranded chromosomes) separate and move to opposite ends of cell
- Chromosomes appear V-shaped when pulled
Telophase
- Chromosomes reform chromatin
- Nuclear envelope (membrane) reappears
- Mitotic spindle breaks up
Cytokinesis
- Division of cytoplasm & organelles
- Begins in late anaphase w/ formation of cleavage furrow (indentation of cell membrane)
- Ends w/ 2 daughter cel
Mitosis (somatic cell division)
- 1 parent cell gives rise to 2 identical daughter cells
- Also, mitosis = nuclear division
- cytokinesis = cytoplasmic division (begins late anaphase)
- occurs in billions of cells each day for tissue repair & growth
Meiosis (reproductive cell division)
- egg and sperm cell production
- in testes & ovary only
Cancer =
Unregulated growth
Benign tumor doesn’t
metastasize (spread)
Malignant tumor can
metastasize (spread)
Two types of cells
Prokaryotic cells
Eukaryotic cells
Prokaryotic cells
single cells
Eukaryotic cells
many cells
*Nucleus
Proteasome
Destroy unneeded or damaged proteins
Synthesis
DNA replication
