Chapter 3: The Cell Flashcards
list basic cell functions
cell metabolism, transport of substances through the cell, communication, and cell reproduction
3 basic components of a cell
plasma membrane, cytoplasm, nucleus
plasma membrane
separates cell body into 2 compartments; the ECF and ICF
ECF
extracellular fluid (outside)
ICF
intracellular fluid or cytosol (inside)
cytoplasm
consists of cytosol, organelles, and cytoskeleton
nucleus
houses most of the cell’s DNA
controls cell’s functions
why do cells vary in size & structure?
it enables them to better perform specialized functions
the plasma membrane is primarily composed of a….
phospholipid bilayer
describe the phospholipid bilayer structure
- the hydrophilic phosphate heads face the
water-containing cytosol and ECF - hydrophobic fatty acid tails face one another
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describe fluid mosaic model
plasma membrane is a fluid, dynamic structure that moves laterally within the plan of the phospholipid bilayer
integral proteins
-embedded in the membrane, with transmembrane proteins spanning across membrane
- helps transport molecules through membrane
peripheral proteins
found on one side of the membrane only
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membrane proteins functions
- May function as channels, carriers, enzymes, or receptors
- They may also provide structural support to cells and tissues.
what type of diffusion is the phospholipid bilayer
selectively permeable
passive transport processes
movement of a substance across the membrane without using ATP
active transport processes
movement of a substance across the membrane against a gradient
REQUIRES ATP
diffusion
a type of passive transport in which solutes move down their concentration gradient until equilibrium is reached
concentration gradient
a situation where a differential concentration of a substance exists, high concentration is present in one location and low concen. is present in another.
simple diffusion
movement of solutes directly through the phospholipid bilayer
facilitated diffusion
molecules diffuse across the plasma membrane with assistance from membrane proteins, such as channels and carriers
osmosis
a type of passive transport in which the solvent moves across a selectively permeable membrane from a region of lower solute concentration to a region of higher concentration
tonicity
The ability of an extracellular solution to make water move into or out of a cell by osmosis
isotonic ECF
- amount of water entering the cell = water leaving the cells
- solution concentration outside cell = solute concentration inside cell
hypertonic ECF
water is transported out of the cell
solute concentration inside cell is LOWER than solution concentration outside cell
hypotonic ECF
water enters the cell
solute concentration is higher inside cell
primary active transport
a membrane protein uses ATP to “pump” a solute against its concentration gradient
One of body’s main pumps is the Na+/K+ pump.
secondary active transport
uses a primary active transport pump to create a concentration gradient, and then uses stored energy from that concentration gradient to pump another solute into/out of the cell against its concentration gradient.
membrane potential
separates thin layer of (+) charges in the ECF and thin layer of (-) charges in the cytosol
vesicular transport
a type of active transport process that allows large substances to enter or exit the cell packaged in membrane-enclosed transport vesicles.
vesicular transport
a type of active transport process that allows large substances to enter or exit the cell packaged in membrane-enclosed transport vesicles.
endocytosis
process by which cells take in substances from outside of cell by engulfing them in a vesicle
can include nutrients to support the cell or pathogens that immune cells engulf and destroy
2 types of endocytosis: Phagocytosis & Pinocytosis
phagocytosis
- the ingestion of bacteria or other material by phagocytes
- crucial in immune system
pinocytosis
cell’s plasma membrane engulfs droplets of ECF, taking in any dissolved material with it
receptor-mediated endocytosis
specific ligands bind to their receptors on the plasma membrane and become concentrated in protein-coated pits
exocytosis
the process by which large substances are packaged into a vesicle that fuses with the plasma membrane and are released from the cell
organelles
specialized components within the cell that carry out specific functions. Most organelles are membrane-enclosed
mitochondria
produce the bulk of the cell’s ATP by oxidative catabolism
stores calcium
peroxisomes
- oxidize toxic substances and fatty acids
- synthesize certain phospholipids
ribosomes
small, granular organelle that makes (synthesizes) proteins
endoplasmic reticulum (ER)
a large branching network of tubules and sacs that enclose a single space
Rough ER (RER)
has ribosomes attached to its surface, and it modifies and folds proteins made by those ribosomes
Smooth ER (SER)
has no ribosomes on its surface
It stores calcium, synthesizes lipids, and detoxifies certain substances
Golgi apparatus
a stack of flattened sacs. It modifies and packages products to be secreted from the cell by exocytosis, to become part of the plasma membrane, or to be incorporated into lysosomes
lysosomes
contain digestive enzymes that break down substances taken into the cell by endocytosis, as well as worn-out organelles
cytoskeleton
gives the cell its characteristic shape and size, supports the plasma membrane and nucleus, moves substances within the cell, divides the cell, and moves the cell itself
actin filaments
abundant beneath the plasma membrane
they form network that provides mechanical support, determines cell shape, and allows movement of cell surface, thereby enabling cells to migrate, engulf particles, and divide
intermediate filaments
flexible ropelike filaments that prevent excessive stretching of cells that are subjected to external/ internal physical forces. provides organelle/structural support.
found in hair and nails
microtubules
are the largest cytoskeleton filaments, supports cell shape, holds organelles in their place, moves organelles within cell, and forms cilia and flagella
microvilli
which increases the surface area of the membrane. Sections that concave down into the surface.
cilia
hairlike projections that sweep substances past the cell
flagella
single projections that propel the cell itself (sperm tail)
nucleus
- contains most of the cell’s DNA
- the control center of the cell
nuclear envelope
surrounds the nucleus
chromatin
genetic material made up of DNA, RNA, and proteins that form into chromosomes within the nucleus
how many chromosomes do humans have?
23 pairs, one maternal set and one paternal set
nucleoli
An area inside the nucleus of a cell that is made up of RNA and proteins and is where ribosomes are made.
protein synthesis
the process by which the cell uses instructions in the DNA to build proteins
gene
a segment of DNA that specifies the amino acid sequence of a single protein
genetic code
the instructions contained in a gene that tell a cell how to make a specific protein
