cell structure and function Flashcards
⬡ Physical separation between the inner cell
and external environments.
⬡ Site of nutrient and waste exchange.
⬡ Sensation of environmental changes or
communication from other cells.
⬡ Structural connection to neighboring cell
Plasma Membrane Functions
- the barrier that surrounds all cells and forms their surface.
- ______are selectively permeable,
meaning only certain molecules can pass. - Small nonpolar- , molecules (CO2, O2) are freely
permeable.
*Large polar molecules - (glucose, proteins,
water) are impermeable without a protein
channel
plasma membrane
the main component of plasma membranes.
⬡ Hydrophobic fatty acid tails are insoluble in water.
- Hydrophilic “Head” (Phosphate)
- Hydrophobic “Tails” (Fatty Acids)
⬡ Hydrophilic phosphate heads are soluble in water.
Phospholipid
–a double-layer sheet where
the hydrophobic tails congregate in the middle.
⬢ Protein-senable communication, transportation, and adhesion
The phospholipids form a bilayer
Water Vapor (H2O)
⬡ Nitrogen (N2)
⬡ Carbon Dioxide (CO2)
⬡ Methane (CH4)
⬡ Ammonia (NH3)
Life began around 4 billion years ago with an
atmosphere that contained..
The _________ was an
experiment constructed to replicate
conditions on the early Earth. ⬡ Electrodes simulated lightning. ⬡ The 5L flask was filled with gases
found in the early atmosphere.
⬡ A 500mL flask contains boiling water
to simulate evaporation from the
oceans.
⬢ After two weeks… ⬡ Carbon was converted to sugars,
amino acids, and parts of nucleic acids.
Miller-Urey Apparatus
The ______explains the importance of
cells to life:
⬢ All living organisms are made of cells.
⬢ Cells express all characteristics of life
(reproduction, homeostasis, etc)
⬢ All existing cells are derived from other
cells.
CELL THEORY
-Prokaryotes- Smaller cells (0.1-0.5μm), No nucleus or organelles, Always single-celled
-Eukaryotes- Larger cells (10-100μm), Nucleus and organelles present, Single or multicellular
TYPES OF CELLS
is the passive movement of molecules from areas of greater to lower concentration.
⬡ The concentration gradient is the gradually changing amount of the particle across a distance
Molecules moving from area of high concentration
to area of low concentration
No energy is required
Occurs because molecules constantly move and
collide with each other
Diffusion
Osmosis
is the movement of water molecules through protein channels called aquaporins.
⬢ Water molecules move towards areas with more solutes(salts, sugars).
- Receptor- Respond to chemical signals, like hormones.
- Carrier- Transport materials across membranes.
- Enzymes- Increase the rate of membrane chemical reactions.
- Anchoring- Attachment to other cells.
- Recognition- Identify the cell as “self” to the
immune system
Types of Membrane Proteins
act as lubricants, adhesives, or part of the cell recognition system
Membrane carbohydrates
- are selectively permeable, meaning only certain molecules can pass.
- Small nonpolar- molecules (CO2, O2) are freely permeable.
- Large polar molecules-
(glucose, proteins, water) are impermeable without a protein channel.
Plasma membranes
Solution Tonicity
*Hypertonic-
Higher concentration of
solute outside of cell.
Water moves out of cell.
Cell shrivels.
*Hypotonic-
Lower concentration of
solute outside of cell.
Water moves in to the cell
Cell bursts.
*Isotonic-
Equal concentration of
solute in and out of cell.
Water moves in and out.
No cell change.
Protein channels allow the
diffusion of molecules that would
otherwise be impermeable.
Passive: No energy required
Facilitated Diffusion
Protein channels move
substances against the
concentration gradient.
Active: requires energy
Active Transport
uses membranous sacs to transport large amounts of material at once.
Vesicular transport
moves material
out of the cell.
Exocytosis
moves material in to the cell.
cell membrane engulfs
the larger molecule and brings it into
the cell
Two types:
◦ Phagocytosis: cytoplasm surrounds a
molecule and packages it in a food
vacuole
◦ Pinocytosis: cell membrane forms
pockets filled with liquid and pinch off to
form vacuoles in a cell
Endocytosis
a type of endocytosis where white blood cell engulf bacteria or viruses whole
Phagocytosis
the fluid found within cells containing nutrients, ion and proteins.
Cytosolis
are individual structures that have specific jobs.
Organelles
The ________ is a network of protein filaments that give the cell structure and support its shape.
cytoskeleton
Fingerlike
extensions that
increase
surface area
Microvilli (cytoskeleton shape)
Cylindrical
structures that
direct
chromosomes
during mitosis.
Centrioles (cytoskeleton shape)
Long, slender
extensions of
plasma
membrane that
can move
independently.
Cilia (cytoskeleton shape)
Very long
extensions of
plasma
membrane that
can move
independently.
Flagella (cytoskeleton shape)
do all the work in a cell, and must be produced and maintained by a series of structures
Proteins
Tiny particles
made of RNA
that build
proteins.
Ribosomes
Rough Endoplasmic
Reticulum (ER)
Network of
membranes covered
in ribosomes.
“Protein factory.”
Membranes with no
ribosomes that build
lipids and
carbohydrates
Smooth
Endoplasmic
Reticulum (ER)
Flattened discs of
membrane that
package proteins in
vesicles.
Golgi
are temporary storage organelles made of a
phospholipid bilayer
Vesicles
Contain material to
be released outside
the cell via
exocytosis.
Secretory Vesicles
Digestive enzymes that
break down worn cell
parts, bacteria, or
viruses.
Lysosomes
- Smaller than
lysosomes
Digest fatty acids and
amino acids. - release a toxic, reactive waste
product called hydrogen peroxide (H2O2) .
⬡ Must be neutralized by an enzyme called
catalase before it damages the cell.
Perioxisomes
the process of cellular respiration to extract
the energy in sugars to release ATP, releasing carbon dioxide and water as waste products.
Mitochondria
Spread
throughout the
nucleus.
Chromatin
Condensed
and tightly
coiled.
Chromosomes
The ________
separates the DNA from
the rest of the cell.
nuclear envelope
______ enable
the movement of
material through the nucleus
Nuclear pores
The _______ assembles
ribosomes.
nucleolus
DNA helicase
the DNA double-helix has to be unwound
with an enzyme
is the process of copying part of
a DNA molecule to a smaller RNA molecule
with an enzyme called RNA polymerase.
⬢ The new mRNA molecule can pass through
a nuclear pore to the rough ER.
Transcription
is single-stranded and uses uracil (U) in
place of thymine (T), following this pattern:
⬡ A→ U
⬡ T→ A
⬡ C→ G
⬡ G→ C
mRNA
sequences of three bases in
mRNA.
⬢ Each codon will translate to a single amino
acid in the protein that will be constructed.
⬡ AUG serves as the start codon.
⬡ UAA, UAG, and UGA are stop codons
Codons
- is the construction of a protein
at a ribosome from the mRNA template.
⬢ mRNA codons are matched up with
tRNA anti codons to ensure the
correct amino acid is added. - After translation, the protein is packaged in
the Golgi for transport
Translation
Each codon
specifies for only
one amino acid.
AUU always
codes for
isoleucine (ILE).
Non
Ambiguous
The same
codon-aminoacid
combinations are
found in all
organisms.
Universal
Each amino acid
has multiple
codons that
signal for it.
Isoleucine (ILE)
s coded by AUU,
AUC, and AUA.
Redundant
The time spent in
between cell
divisions.
Cells grow and
perform their normal
tasks during this
time.
Interphase
The division of the
nucleus into two
identical copies.
Mitosis
The division of
the cytosol and
organelles.
Cytokinesis
The nucleus directs the activities of the cell
through the building of proteins
Protein Synthesis
Fluid Mosaic Model
Example:
-Proteins: forms channels and pumps to
move materials across membranes
- Carbohydrates: act like identification cards
so cells can identify one another
Energy is not required for
movement across the membrane to
occur
Molecules move from area of high
concentration to area of low
concentration
Example: Like riding a bike downhill
-Two factors determine if passive
transport takes place, equilibrium
and permeability
Passive Transport
when the concentrations on
both sides of the membrane are equal
Equilibrium
- ability of a molecule to diffuse (move) across a membrane
- Impermeable: molecules that cannot
pass across a membrane - semi-permeable/selective permeability:
Some molecules can pass across the
membrane while other molecules cannot
Permeability:
Energy required for molecules to pass across
◦ ATP – the “battery” of the cell
◦ Breaking a bond in ATP releases energy
◦ Can “pump” molecules from low to high
concentration (against concentration gradient)
Active transport
cytoplasm surrounds a
molecule and packages it in a food
vacuole
Phagocytosis(endocytosis)
cell membrane forms
pockets filled with liquid and pinch off to
form vacuoles in a cell
Pinocytosis(endocytosis)
