cells Flashcards
three compartments of cells
- plasma membrane
- cytoplasm
- nucleus
Nucleus
what does it control?
what is DNA?
What is nucleus surrounded by and what are nucleus pores
Control centre for the cell
- controls protein synthesis
Contains DNA
- Genetic material
- Blueprint for the activity of all cells
Surrounded by the nuclear envelope
- nuclear pores allow movement of molecules into and out of the nucleus
Ribosomes
What are the two types and their functions and where they are founds
Free ribosomes
- suspended in cytosol
- makes proteins that mostly function in the cytosol
Membrane-bound ribosomes
- Bound to endoplasmic reticulum
- Creates proteins that mostly function in membrane or outside of the cells
Proteins that function within organelles are made by either free or membrane-bound ribosomes
Cytoplasm
consist of? and fluid type
Organelles
- cellular organs
- mostly surrounded by a membrane
- Jelly-like fluid
Inclusions
- Chemical substances eg. stored nutrients and pigments
Cytoplasm organelles
Endoplasmic reticulum
Golgi apparatus
lysosomes
peroxisomes
mitochondria
Endoplasmic reticulum what is it and two types
Extensive network of membranes joining the nucleus
Two types
- rough ER
- smooth ER
Job of rough endoplasmic reticulum and smooth endoplasmic reticulum
Rough
- covered in rough ribosomes
- makes proteins
- Packages and transports proteins to the golgi apparatus in transport vesicles
- Acts as a membrane factory
Smooth ER
- has specialised functions in particular cells
e.g.
- Detoxifications- liver and kidneys
- making steroid-based hormones like testies
- Releasing calcium for muscle contraction- skeletal and cardiac muscles
Golgi apparatus
Series of curved sacs
The golgi apparatus accepts transport vesicles from the ER for futher processing
- Proteins are modified, sorted and shipped to their final destination
- outside the cell
- to the various membranes
- organelles
Lysosomes and peroxisomes
Membrane bound vesicles containing enzymes
Bud off from the ER or Golgi apparatus
lysosomes
- Break down organic material inside the cell like bacteria, old organelles
Peroxisomes
- Degrade toxic molecules inside the cell
Mitochondria
Power plant of the cell
carries out aerobic cellular respiration
- Nutrients in food converted to CO2 and H2O
- Released energy is stored as ATP (adenosine triphosphate)
Adenosine triphosphate (ATP) what it is and what does it become after one is removed
The chemical bond between the last two phosphate groups is broken
Energy is released when terminal phosphate group is removed
ATP becomes ADP
Why do we use ATP?
Synthesis of new compounds e.g protein
Transport of molecules across membranes
Mechanical work e.g contraction of muscles cells
Phospholipid bilayer
Two layers of phospholipids
phospholipids have a head and two tails
the head is
hydrophilic
negatively charged,
polar
the fatty-acid tails are hydrophobic
non-polar
uncharged
Plasma membrane - 4 functions
- Forms a mechanical barrier
- separates intracellular fluid (ICF) from extracellular fluid (ECF)
- Selective permeability
- Determines which molecules can move between the ICF and ECF - Electrochemical gradient
- Important for neural and muscle function
- direction of ions - Communication and cell signalling
- Receiving and interpreting messages from other cells
two types of transport across the plasma membrane
Passive
- Does not require cellular energy
- Molecules move from high concentration to low concentration down the concentration gradients
active
- requires cellular energy ATP
- molecules move from low concentration to high concentration- against the concentration gradient
three types of passive and
three tpes of active transport
Passive
-simple diffusion
- Facilitated diffusion (channels and carriers)
- Osmosis
Active transport
- primary active transport
- secondary active transport
- vesicular transport (endocytosis and exocytosis)
Diffusion
what is it?
The movement of molecules form an area of high concentration to an area of low concentration (down the concentration gradient)
- Molecules are in constant random motion
- Collisions cause the molecules to spread out
The molecules will eventually reach an equilibrium
Facilitated diffusion
- Non-penetrating solutes can only diffuse across the plasma membrane through carriers or channeles (they need to be “facilitated”)
- Carriers interact with the molecules and move them to the other side
e.g. glucose transporters - Channels act like tunnels through the membrane
e.g. Ino channels in neurons
Osmosis
The movement of water across a selectively permeable membrane from an area of low osmolarity to an area of high osmolarity
Osmolarity is the number of solute particles in the solution ie. the concentration.
Solute molecules are prevented from moving but water moves by osmosis volume increases in the compartment with the higher osmolarity
In the end, both solutions have identical osmolarity but volume of the solution on the right is greater because only water is free to move.
Tonicity and isotonic solution
The effect that a solution has on cell size and shape due to water movement (osmosis)
Isotonic solution
- Solution has the same osmolarity of non-penetrating solutes compared to the cells
Hypotonic solution
- lower osmolarity of nonpenetrating solutes in the solution compared to the cell
Water moves into the cell
The cell will swell
hypertonic solution
Higher osmolarity of nonpenetrating solutes in the cells
water moves out of the cells
the cell will shrink
Active membrane transport
Uses energy (ATP) to move molecules across the plasma membrane
Active transport
- Uses energy to move molecules against their concentration gradient
- Two types
- Primary active transport: directly uses energy from breakdown
- Secondary active transport: Uses energy stored in ion concentration gradient created by primary active transport. Indirectly uses ATP
- Vesicular transport
Describe Primary active transport
VIDEO
Secondary active transport
- Always move more than one molecule at a time
- One molecule usually an ion will move down the concentration gradient, providing the energy source.
- The other molecule will hitch a ride at the same time, so that it can move against the concentration gradient.
Vesicular transport
Transfer of materials between ECF and ICF within vesicles
- Fluid-filled sacks enclosed by membrane
- Requires energy from ATP
- Exocytosis
- Vesicular transport OUT OF the cell - Endocytosis
- Vesicular transport into the cell - Sometimes a cell needs to transport substances which are too large for carriers so they use vesicular transport
Division of the ANS
