Exam 2 Flashcards
Desmosomes
Hold adjacent cells together but materials can move around the EMC
Gap Junctions
Similar to plasmodesmata
Channels which run between membrane pours in adjacent cells allowing substances to pass between cells
Heart cells
Tight junctions
Prevent movement of substances between cells
Skin
Cell theory
Cells are the basic units of life
All organisms are composed of cells
Cells come form other pre existing cells
Why do cells need to be small?
As the cell gets bigger its volume increase more quickly than surface area
A large cell doesn’t have enough surface area to efficiently move substances in and out
Light microscope
Visible light shined on through a cell Size limit (0.2um) Living cells and general cell structure
Electron microscope
Electron beam focused by magnets
Size limits (2nm)
Structures within preserved cells
Phagocytosis
Cell eating
Engulf large particles or even entire cells
Pinocytosis
Cell drinking
Smaller vesicles and dissolve substances into cell
What structures facilitates cell communication in plant cells?
Plasmodesmata
Which of the following substances would pass through the cell membrane most easily?
Small, non-polar molecule
What would be the effect of placing an animal cell in a hypotonic solution?
The water in the solution would move via osmosis into the cell and cause it to lyse
Which of the following would result in the ingestion of a wide variety of soluble nutrients from the environment?
Pinocytosis
In which phase does a normal cell make the commitment to divide or not?
G1
Which one of the following cytoskeletal structures has the smallest diameter?
Microfilaments
Shared features of all cells
Cells separate the internal from external environment in order to maintain homeostasis
Cells must store information and pass it onto the next generation
Cells must be able to build proteins
Cells must conduct the chemical processes of life
Prokaryotic cell structures include
Nucleoid
Ribosomes
Plasma membrane
Cytoplasm (cytosol and insoluble particles ribosomes).
Specialized features of some prokaryotes
Cell walls
Flagella
Cytoskeleton
Cell walls prokaryotes
Outside plasma membrane
Rigid
Contains peptidoglycan and outer membrane
Flagella definition continued
Appears as a tiny corkscrew
Spins on axis
Cellular movement
Cytoskeleton prokaryotic cells
Often found within rod shaped bacteria just inside of plasma membrane
Maintains
Eukaryotic cells have
Compartmentalizations and membrane bound organelles
Compartmentalization is key to
Eukaryotic cell function
Nucleus
Storage of DNA Hereditary information stored in sequence of DNA nucleotides Largest organelle Most cells contain 1 Chromatin is DNA + proteins
Chromosomes
Long thin threads of chromatin
Structure of nucleus
Nuclear envelope (2 lipid bi layers continuous with membrane of the endoplasmic reticulum) Nuclear pores (1000's, connect interior nucleus to cytoplasm) Nucleolus (make rRNA and ribosomal subunits
Ribosomes
Site of protein synthesis
Components of cytoskeleton
Microfilaments
Intermediate filaments
Microtubules
Microfilaments
Strands of actin
Diameter 7nm
Function: movement, determine/stabilize cell shape, resist tension
Actin monomers attach to (+) end and detach at the (-) end
Processes involving Microfilaments: cytoplasmic streaming and formation of pseudopodia
Smallest
Actin
At positive end it attaches and at the negative end it detaches
Polymerization is the process of adding actin to the positive end
Intermediate filaments
Diameter (8-12 nm)
Fibrous proteins organized into tough rope like structures
Function: anchor cell structures and resist tension
50 different kinds (cell type specific)
No dynamic instability
Fibrous proteins
Rope like
Microtubules
Diameter (25 nm)
Long, hollow cylinders made of Tubulin (unbranched)
Function: rigid internal skeleton, framework for motor proteins to move structures within the cell
Organize chromosomes (mitosis)
Movement of cilia and flagella
13 chains of dimers make a hollow tube
Cells shared features
Internal/external homeostasis
-plasma membrane (gatekeeper and phospholipid bi layer).
DNA
Ribosome (organelle of protein synthesis)
Cytoplasm-location
Prokaryotic cells
Pro – before No nucleus Domain Archaea Bacteria No membrane enclosed organelles DNA (1 circular chromosome - plasmids) Cell membrane Smaller Nucleotide: region where DNA is located Ribosomes: protein synthesis
Nucleoid
Region where DNA is located
Ribosome prokaryotic
Protein synthesis
Eukaryotic cells
Eu-good/true Presence of nucleus Domain Eukarya (protists, fungi, plants, animals) Membrane enclosed organelles – compartmentalization DNA: linear chromosomes Cell membrane Cell wall – plants 10x larger
Plasma membrane
Encloses cell
Separate interior from exterior
Regulate traffic into and out of cell
Cytosol
Water with dissolved ions, small molecules, biomolecules, proteins
Anything that is insoluble is suspended in the cytosol
cell wall
Outside of plasma membrane
Rigid – support cell, determine shape
Peptidoglycan
Outer membrane polysaccharide and phospholipid
Peptidoglycan
Sugars and peptides
Single, large molecule
Capsule
Outside cell wall
Prevent drying out
Evade immune system
Helps bacteria attach to others
Flagella
Swim Protein - flagellin Long (10-200um) Single or in pairs Push/pull through environment
Cytoskeleton
Cytoskeleton skeleton is behind plasma membrane maintains structure
all cells have
Plasma membrane
Cytoplasm
Ribosomes
DNA
Organelle
Structure in a cell that performs a specific function
Functions of nucleus
Process information from cytoplasm
Store and retrieve information – chromosomes – polynucleotides
Location of replication and transcription
Contains nucleosis where ribosomes are assembled (Rna and proteins)
Allow ribosomal subunits to leave through pores
Ribosome
Protein synthesis – translation
RNA – protein
No membrane
Can be free in cytoplasm or attached to rough ER
Endomembrane system
Very large
Vesicles
vesicle
Tiny membrane enclosed structure that shuttle substances throughout components of cell or to the plasma membrane
Nuclear envelope
2 lipid bilayer
Nuclear pore: connect nuclear interior to cytoplasm
Nuclear pore
Connect nuclear interior to cytoplasm
Endoplasmic reticulum
Expensive folding – increased surface area
Rough – ribosomes
Smooth – no ribosomes
Protein synthesis (rough er)
Rough endoplasmic reticulum
Ribosomes
Protein synthesis
Smooth endoplasmic reticulum
Lipids synthesis
Carbohydrate metabolism
Calcium storage
Breakdown toxic substances
Golgi apparatus
Cis face- close to nucleus and ER
Trans face- cytoplasm
Lysosomes
Digestion and recycling
Phagocytosis
Breaks Down materials
Peroxisome
Detoxify cells
H2O2
Break down peroxide
Mitochondria
Transform energy
Outer- large pores, passage of substances
Inner- biochemical processes
Plastids
Plant/algae
Chlorophyll
Light to chemical energy
Granum
Stack of thylakoids
Vacuole
Contractile: continual diffusion of water
Central: storage of ions, water, toxins
Cytoskeleton
Support and shape
Controls position/movement of organelles
Move cytoplasm
Anchor cell
Dynamic instability
Proteins of the cytoskeleton maybe made or broken very rapidly
Depolymerization
Releasing from the negative end
Anchor
Radiate from the nuclear envelope
Holds nucleus in place
Holds organelles in place
Desmosomes are also
Junctions between cells
Microtubules are also
Cylinders
Framework for motor proteins to move structures within the cell
Organize chromosomes
Motor proteins
Help movement along 1 microtubules
2 Microtubules along each other
Cillia
Short (2-20um)
Hundreds per cell
Stiff movement (protists)
Move substances in respiratory tract
Dynein
ATP hydrolysis to allow Microtubules to slide pass each other (cilia and flagella)
Nexin
Holds two Microtubules together
Causing bending
Kinesin
Movement of vesicles, organelles, chromosomes
Walks across Microtubules
Plasmodesmata
Plasma membrane blind channels that connect adjacent cells
Exchange between the cells
Water, ions, small molecules, hormones, RNA, proteins
Membrane
Retain materials, maintain homeostasis, protect contents of a cell
Apoptosis
Cell detaches from neighbors DNA hydrolyzed Formation of membrane blebs Blebs break into small fragments Other cells (often macrophages) ingest cellular remains Digestion in lysosomes
Necrosis
Cells swell, bursts, and release contents to extracellular environment
causes inflammation
Why is cell death necessary?
Longer cellular life equals more prone to accumulation of DNA damage, leads to cancer
cells no longer needed
CDK
Regulate cell cycle checkpoints
Checkpoints
Times when the cell cycle can be stopped or pushed forward
Eukaryotic cells do not constantly
Divide
Signals linked to division are linked to organisms needs
Bacterium constantly
Divide
When nutrients go down, they stop dividing
Translocations
During crossing over of Meiosis one, movement of a portion of a chromosome to a non-homologous chromosome, results in addition of extra genes to chromosomes
Aneuploidy
Improper number of one of the chromosome pairs
Monosomy
Missing a chromosome
Trisomy
Possessing an extra chromosome
Nondisjunction
Failure of homologous chromosomes (anaphase 1) or sister chromatids (anaphase 2) to separate
Simple diffusion
Energy: no
Driving force: concentration gradient
Membrane protein: no
Specificity: n/a
Facilitated diffusion
Energy: no
Driving force: concentration gradient
Membrane protein: yes
Specificity: yes
Active transport
Energy: ATP
Driving force: (against gradient) energy->ATP
Membrane protein: yes
Specificity: yes
Passive transport
No required energy
1 simple diffusion
2 facilitated diffusion
Active transport
Requires energy
Diffusion
Random movement toward equilibrium
1 Diameter of molecules (smaller equals faster) 2 temperature (higher temp = faster) 3 Concentration gradient (higher = faster)
Dynamic equilibrium
Molecules/ions contains to move randomly across membrane, but concentrations are equal
Osmosis
Diffusion of water across a semipermeable membrane
Higher the solute = decrease in water
Water moves toward solute
Tonicity
Measure of tendency of water to move from one area to another when separated by selectively permeable membranes
Uniport
One substance
Single (along the gradient)
Symport
Two or more Same direction (along the gradient)
Antiport
Two or more Opposite direction (along individual gradients)
Pump
Active transport protein, use energy ATP, move substances against concentration gradient
Sodium – potassium pump
3 na+ and ATP bind to pump
ATP hydrolysis -> ADP + P
Pump shape change -> 3NA+ released 2K+ bind to pump outside
Po released and pump returns to original shape
