Chapter 6/7/8 - Cell Membranes Flashcards
Cell Theory
- All organisms are composed of 1 or more cells , and life process of metabolism and heredity occur within these cells
- Cells are the smallest living things and and are the basic unit of organization in all living organisms
- Cells arise only by division of pre existing cells
True or false
Life represents a continuous line of descendants from those early cells
True
What is the reason why cell are small ?
Diffusion into and out the cell
The small size of cells allow
Diffusion to occur easily
Lower energy expenditure
Lower waste
Surface are to volume ratio
Volume increases rapidly as a cell increases in size
1-10um in diameter
Prokaryotes
10-100um in diameter
Eukaryotes
How do we visualize cells
With use of technology (microscopes)
- cells are not visible to the naked eye (resolution)
What is the purpose of chemical stains
Chemical stains aid the resolution of cells, make them more visible through a microscope
What are the 4 major components of a cell?
- nucleoid or nucleus
- cytoplasm
- ribosomes (synthesize proteins)
- plasma membrane
Production of protein is achieved by
Ribosomes
How many subunits make up a ribosome
2
Large subunit
Small subunit
The area of a prokaryotic cell (simplest organism)
Nucleoid
Eukaryotes (complex organisms) are contained in the
Nucleus
The nucleus is surrounded by a double membrane called the
Nuclear envelope
What is cytoplasm?
What does it contain?
Semi fluid matrix that fills the cells interior
Contains sugars, amino acids, proteins, and organelles used to carry out daily activities.
Cytosol
The part of the cytoplasm that contains organic molecules and ions in solution
Organelle
Specialized part of a cell, small cytoplasmic organ
Separates the inside of the cell from the outside environment
plasma membrane
Plasma membrane is composed of
Phospholipids and contains membrane proteins
What is embedded in the plasma membrane
Proteins
Phospholipid molecule make up the
Plasma membrane
What is responsible for the cells ability to interact with the environment
Proteins of plasma membrane
Lacks membrane bound nucleus, internal membrane system, and membrane bound organelles
Prokaryotes
Prokaryotes are small simple cells surrounded by
Cell wall
True or false
Prokaryotes have no compartments
True
Prokaryotes lack
Membrane bound organelles
Lack cytoskeleton found in eukaryotes. But have elements of actin and tubulin to help maintain its structure
Prokaryotes have
Free floating ribosomes to synthesize proteins
Name two types of prokaryotes
Bacteria
Archaea
Bacterial cell wall is composed of
Peptidoglycan , a sugar polymer
Functions of bacterial cell wall
Protect the cell
Maintain its shape
Prevent excess uptake or loss of water
Archaea Cell Wall is composed of various chemical compounds such as
Proteins
Polysaccharides
Inorganic compounds
Archaea Cell Membrane
A fatty acid chain (saturated hydrocarbon) that is covalently attached at both ends to glycerol, creating a monolayer rather than a bilayer
Can archaea adapt to changing environmental temperatures?
No. Unable to alter the degree of saturation of hydrocarbons
The cellular machinery that replicates DNA and synthesized proteins in archaea is more closely related to
Eukaryotic systems than bacterial systems
Long, threadlike structures protruding from the surface of a cell that are used for locomotion(movement)
Flagella
Prokaryotic Flagella
Protein fibers that extend out from the cell wall.
(Rotary Motor)Movement powered by proton gradient
There may be one or more per cell, or none depending on species.
Eukaryotic Cells
Contains an endomembrane system that allows the inside to be compartmentalized —- this allows biochemical reactions to occur independently and simultaneously through organelles
Common organelles found in animal, fungi, and plant cells
Nucleus Nucleolus Ribosomes Cytoplasm Endoplasmic Reticulum(rough/smooth) Golgi Apparatus Lysosome Peroxisome Plasma Membrane Mitochondria Cytoskeleton (actin filaments, microtubules)
Largest organelle, spherical in shape, typically located in the center of a cell
Nucleus
The nucleus contains ______________
Which are packaged DNA, or gene coding for protein
Chromosomes
All eukaryotic cells are supported by an internal protein scaffold called
Cytoskeleton
DNA are packed to form_____________ which are further packed by proteins to form_______________
Chromatins
Chromosomes
Two phospholipid bilateral that surrounds the nucleus
Nuclear Envelope
Describe the nuclear envelope
One layer surrounds the nucleus
The outer phospholipid bilayer forms the endoplasmic reticulum, or cytoplasm interior Membrane system
The outer phospholipid bilayer of the nuclear envelope forms the
Endoplasmic reticulum
Network of intermediate filament fibers that covers the inner surface of the nuclear envelope , which give the nucleus its shape
Involved in the deconstruction and reconstruction of the nuclear envelope that accompanies cell division
Nucleus lamins
Found embedded between two phospholipid bilayers
Scattered over the surface of the nuclear envelope
Nuclear pores
Nuclear pores allow
- Ion and small molecule exchange or diffuse between nucleus and cytoplasm
- controlled transport of large proteins and RNA, RNA - protein complexes into and out of the nucleus
Nucleolus is found within
The nucleus
Houses ribosomal RNA genes, RNAs, and ribosomal proteins within itself during ribosome production
Nucleolus
Manufactures ribosomal RNA subunits (ribosomes) needed to synthesize protein
Nucleolus
Organelle within a cell that is important in synthesizing protein
Ribosome
Newly made protein is found in the
Cytoplasm
The large subunit and small subunit of ribosome is composed of a combination of RNA called
- rRNA, or ribosomal RNA
2. Proteins
Subunits of ribosome form only when
They are actively synthesizing proteins
Messenger RNA (mRNA)
Carries coding information from DNA
Transfer RNA (tRNA)
Carries amino acids
Ribosomes use the information in mRNA to direct the
Synthesis of protein
Ribosomes are found
Free in the cytoplasm
Associated with internal membranes
Embedded in the ER
Contains the message or protein sequence to be made
mRNA
Will read the mRNA and translate it into an amino acid chain
rRNA(ribosomes)
Will provide the amino acids to build the growing peptide chain
tRNA(ribosomes)
Factories that make proteins
Ribosomes
Cell interior contains an endomembrane system that
Divides the internal cell into compartments
What forms the largest endomembrane?
Endoplasmic reticulum
Exists as folded membranes, tubular networks, and other shapes
Endoplasmic reticulum
Phospholipid bilayer forms the
Endoplasmic reticulum
Cisternal Space/ lumen
Interior of ER
Two types of ER
Rough ER
Smooth ER
Rough ER
Ribosomes embedded in membrane (hence, rough, bumpy appearance)
Synthesizes proteins on the surface of ER(where ribosomes are located)
Fluid component of the cytoplasm containing dissolved organic molecules such as proteins and ions
Cytosol
What are the two largest compartments in eukaryotic cells
Cisternal space
Cytosol
Proteins synthesized on the surface of the rough ER are destined to be exported from the cell to
Lysosomes or vacuoles
Or
Embedded in the plasma membrane
Where is the site for protein synthesis?
Rough ER
Determines wether the ribosome will become associated with the rough ER or remain a cytoplasmic ribosome
The sequence of proteins being synthesized
On the surface of the rough ER , synthesized proteins will enter the ____________ of the endoplasmic reticulum , where protein modification occurs
Lumen , cisternal space
Where are NEWLY SYNTHESIZED proteins modified by the addition of of Carbohydrates to form glycoproteins
Endoplasmic reticulum
How are newly synthesized proteins modified
By the addition of carbohydrates to form glycoproteins
GLYCOPROTEINS - ( destined for secretion, are separated from other products and later packaged into vesicles that move to the Golgi for further modification and packaging for transport of other cellular locations)
What type of ER is this?
1) ribosome embedded on surface
2) synthesizes proteins
3) synthesized proteins enter lumen of ER, and are modified
4) proteins are sorted, further packages for the Golgi apparatus
5) proteins exported cytosol, lysosome, or vacuole, or embedded in plasma membrane
Rough ER
Regions of the ER with very few bound ribosomes
Smooth ER
Name structures of smooth ER
Tubules, flattened sacs, tubular arrays
Smooth ER membrane contains
Enzymes
Enzymes in the ER are involved in the synthesis of
Carbohydrates
Lipids
Steroid hormones
An important function of the smooth ER is to store
Intracellular Ca2+
- this keeps the cytoplasmic level low , allowing Ca2+ to be used as a signaling molecule
What is Ca2 + ?
A signaling molecule
What does Ca2+ trigger?
Muscle contraction
Intracellular contraction
Where is Ca2+ stored
Smooth ER
What does the Smooth ER modify? Why?
Foreign substances to make them less toxic , detoxify harmful substances
Ex: liver cells have large smooth endoplasmic reticulum —> neutralizes substances in the liver
Collection of flattened sac membranes
Golgi apparatus
Individual membrane sacs of the Golgi apparatus are called
Cisternae
- Proteins and lipids manufactured on the rough and smooth ER are transported into the _____________ and modified as they go through it ,
- materials then bud off as secretory vesicles on the _____________
Golgi Apparatus
Trans Face
Name three things the Golgi Apparatus does to molecules
Assembles
Packages
Distributes
cis face?
Front of Golgi
Trans face?
Back of Golgi
In plant cells, noncellulose polysaccharides that form part of the cell wall of plants/ are composed here and brought to the plasma membrane
Golgi Apparatus
Lysosome arise from
Golgi Apparatus
Lysosomes contain
High levels of degrading enzymes
What do degrading enzymes in lysosome do?
Catalyze the rapid break down of proteins, nucleic acids, lipids, and carbohydrates
Degrades old cellular organelles(makes room for new organelles)
As phagocytosis (eats) wastes, a proton pump pushes H+ into the lysosome, decreasing the pH. Why is this significant?
Activates digestive enzymes in lysosome
Leads to destruction of old organelle
Membrane enclosed vesicles that contain enzymes needed for metabolism
Microbodies
True or False
Peroxisome is a microbody
True
Microbody which contains enzymes involved in the oxidation of fatty acids.
Peroxisome
Peroxisomes form from the __________________, which can ________________________
The cushion of ER vesicles
- ER vesicles can uptake peroxisomal enzymes, grow, and divide
Hence peroxisome breaking down fatty acids through oxidation, the resulting byproduct is _______________. Peroxisome contains ______________ to further beak this down
Hydrogen peroxide
Catalase (breaks down to water/hydrogen)
Tubular organelle
About the size of bacterium
Found in all eukaryotic cells
Mitochondria
What 2 membranes does mitochondria contain
Smooth outer membrane
Inner folded membrane
What are the layers in the inner folded membrane called
Cristae
In mitochondria, What does cristae form
Matrix
-inner membrane
Intermembrane space
- outer compartment
In the mitochondria, proteins are embedded on________________ which carries out______________ to create atp.
The inner membrane (matrix)
Oxidative metabolism
Mitochondria is considered a cell within a cell because it has its own
DNA , which produce proteins
True or false
Mitochondria can divide to form new mitochondria
true
Supports the cell shape
Anchors organelles
Allows proteins to be distributed throughout the cell
Allows cell movement
What am I?
Cytoskeleton
What is the cytoskeleton composed of?
Protein fibers
Actin filaments
Microtubules
Intermediate filaments
Composed of 2 protein chains loosely twined together
Exhibit polarity, has a + and - end.
Concentrated in bundles below the plasma membrane, known as stress fibers
Responsible for cellular movements such as crawling, “pinching” during cell division, formation of cellular extensions
What am I?
Actin filament
Largest of the cytoskeleton elements
Hollow tubes, each composed of a ring of 13 protofilaments (a- & ß- tubulin polymerize to form ring)
Protofilaments line up side by side around core to form hallow tube, give it shape
What am I?
Microtubule
Name 3 characteristics of microtubules?
Facilitate movement
Organize the cytoplasm
Responsible for moving materials within the cell
Formed from proteins such as vimentin, keratin, or neurofilaments
Once formed does not break down
Stability and shape of cell (protein->vimentin)
Most durable element in cytoskeleton in animal cells
What am I ?
Intermediate filament
Centrioles are found in
Animal cells
Most Protists
In animal cells, what is found in pairs and at right angles to each other near nuclear membranes
Centrioles
Region surrounding centrioles is the space called
Centrosome
Surrounding the centrioles(pairs) in the centrosome is the
Pericentriolar material
Contains tubulin and materials needed to convert tubulin to microtubules
Pericentriolar material
Microtubule organizing center
Organizes microtubules during cell division
Centrosomes of plants and fungi lack
Centrioles
***Contain microtubule organizing center
Animal Cells: Extracellular matrix
What two proteins are secreted?
Where are the proteins secreted?
What does it form?
Glycoproteins and proteoglycans
Into the surrounding space
Forms protective cushion around cell
Plant cells: Cell Wall
Protects and supports
Primary wall produced in young cells
True or false
Chloroplast is absent in animal cells
True
Plant cells contain a cell wall
True or false
True
Animal cells lack cell wall.
True or false
True
The extracellular matrix is composed of
Glycoproteins, collagen, and elastin
Sticky substance released by plant cells to adhere to adjacent cells
Middle lamella (within cell wall)
structure found in many plant cells, located between the primary cell wall and the plasma membrane.
Deposited Inside primary wall of fully expanded cells
Ex:
- cell 1 (primary)
- cell 2
Secondary cell wall
Plant cells have specialized membrane bound structures called
Vacuoles
Tonoplast
Membrane surrounding large central vacuole
Contains channels that are used to help the cell maintain it tonicity
Tonoplast
Plant cells: What do vacuoles store?
Water
Sugars
Ions
Other molecules
Plant Cell:
Vacuole helps to maintain plant cell _____________, which allows plant cell______________
Tonicity
Growth
Plant Cell:
Found in plant cells and any cell that uses the suns energy to carry out photosynthesis
Chloroplasts
Plant Cells:
Allows cell to make their own food
Chloroplasts
Plant Cells:
Outer and Inner membrane , larger than mitochondria
Chloroplasts
Plant Cells :
Inside the inner membrane of chloroplasts are stacks of membranes called
Grana
Plant Cells: Chloroplasts
What is grana composed of?
Several thylakoid disks
Plant Cell: Chloroplasts->Grana
What does the surface of thylakiod disks contain?
Photosynthetic pigments , or chlorophyll
Plant Cell: chloroplasts-> grana-> thylakoids
Fluid matrix that surrounds thylakoids and contains enzymes to synthesize glucose
Stroma
Plant Cells:
Chloroplasts is considered a cell within a cell because it contains
DNA
Plant Cells:
Chloroplasts and Mitochondria arose by
Endosymbiosis
Plant Cells:
Theory that eukaryotic cell arose by symbiosis between two cell that were once separate
Symbiosis def. - (interaction btw 2,beneficial for both)
Endosymbiosis
Cell Movements: Intracellular
Transport of materials are performed along_________
Microtubules
Cell Movements: intracellular
Requires 4 components which are?
Vesicles or organelle to be transported
Motor protein that does the moving
Connector molecule that holds the cargo
Microtubule as the track
Cell Movements : Extracellular
Why do actin filaments rearrange intracellularly
I’m to allow cells to crawl
“Crawl cell” destroy pathogens
Cell Movements: Extracellular -> Crawl Cell Process
- Actin filaments in leading cell quickly polymerize to ___________________
- Then, Microtubules polymerize to __________
- Lastly, actin in trailing end depolymerizes to _________________
- To stretch cell forward
- To stabilize the leading end
- To contract the cell towards its body
Cell Movements: Extracellular
Aids in propelling a cell
Evolved early on in Eukaryotes
Circular shape consisting of 9 microtubule pairs arranged in a ring structure and surrounds 2 central microtubules (9 + 2 structure)
What am I?
Flagella
Cell Movements: Extracellular -> flagella
What is it’s motor protein?
What does the motor protein cause?
Dynein
Causes microtubules to move past each other in UP - DOWN WAVES
Cell Movements: Extracellular
More modern and evolved form of flagella used in multi cellular eukaryotes
Similar (9 +2) structure arrangement as flagella
Arranged in rows & shorter than flagella
Cilia
Cell Movements: Extracellular
What are functions of cilia?
Propels water
Increases surface area
Important in secretion and absorption
Wall layer deposited during the period of cell expansion
Primary wall
Cell Communication
Cells need a way to communicate with each other (T/F)
More specializations give rise to different populations of cells(T/F)
True
True
Cell communication
Set of genes that function to mark the surfaces of cells, identifying them as being a particular type
Surface Proteins (MHC)
Cell communication : Surface proteins
Tissue specific cell surface maker
On the surface of red blood cells
Responsible for A, O, B blood types
Glycolipids
Cell Communication: surface proteins
Found on virtually all cells in an organism that communicates “self” from anything that is “non-self”. Ex: cells in immune system defend against invading cells
What am I?
MHC proteins
Cell communication
Name the various junctions
Gap
Adhesive
Communicating
Cell Communication
Electrical signal driven by chemical means
Action potentials
Cell communication
Identifying cell markers?
Surface proteins
Cell Communication
Name all cell to cell connections
Adhesive junction
Adherens junction
Desmosomes
Cell Communication
Name all Communicating junction
- gap junction
- plasmodesmata (plants)
Cell Communication
Junction found in tissues subject to mechanical stress
Attach cytoskeleton of a cell to cytoskeleton of of other cells or extracellular matrix
Found in all animal species
What am I?
Adhesive junction
Cell Communication
Based on the protein cadherin (Ca2+) , which is a single transmembrane protein that protrudes into the extracellular space
Can join with cadherin of adjacent cell
Adheren junction
Cell Communication
Join adjacent cells via the cadherins DESMOCOLLIN & DESMOGLEIN , which interact with intermediate filaments of the cytoskeleton
Unique to vertebrates
Support tissue against mechanical stress
What am I?
Desmosomes
Cell Communication
Found in both invertebrates and vertebrates
Forms a barrier to seal off a sheet of cells
Separate junction
Cell Communication
Found in vertebrates
Contains claudins (protein)
Blocks substances from passing between cells
Creates sheets of cells to prevent substances from crossing (nutrients absorbed from food must pass through sheet) Ex: stomach
Tight Junction
Cell Communication
Allows diffusion of molecules between cells through small openings
Permit small molecules or ions to pass from one cell to the other
Communicating junction
Cell Communication: communicating junction
Direct communication channels between cells
Found in invertebrates & vertebrates
In invertebrates I AM formed by pannexins
In vertebrates I AM formed by connexons
I AM found in ANIMAL CELLS
What am I ?
Gap Junction
Cell Communication:
Pannexin/ connexon from two cells line up to form a
Gap junction
Cell Communication:
Cytoplasmic connections that form across the touching plasma membranes
A central tube that connects the Endoplasmic reticulum from 2 adjacent plant cells
In plants, cell to cell junctions occur only at holes or gaps in walls
What am I?
Plasmodesmata (in plants)