Topic 1-5: Cell Structure, Function, Movement & Communication Flashcards
Explain the Cell Theory
- All orgnisms are made up of cells
- Cells are the basic unit of life
- Cells come from pre-existing cells that have multiplied
Describe the 2 types of cells
Prokaryotes: no nucleus, no cytoskeleton, no cytoplasmic organelles, singular circular DNA molecule
Eukaryotes: nucleus, cytoskeleton, and cytoplasmic organelles are present; multiple linear DNA molecule
What are tissues?
Complex organizational arrangments of cells that are similar in structure and function
Groups of tissues form what?
Organs, containing different combinations of tissues types
Groups of cells form
Cells –> tissues –> organs –> organ systems
What is the process in which cells need to die in order to form new cells?
Apoptosis: programmed cell death
Break down the water component in our body
2/3 is intracellular fluid (ICF)
1/3 is extracellular fluid (ECF) = 20% blood and 80% interstitial fluid
Functions of nucleus
The control center of the factory “cell”. It stores chromosomes which contains DNA, the information needed for cell processes as well as making proteins.
Describe nucleolus
A site where RNA transcription and ribosomes biogenesis happen
What are the differences between rough and smooth endoplasmic reticulum?
Rough ER: synthesise and fold ribosomes + proteins
Smooth ER: lipid and steroid hormone production
What organelle is responsible for distributing proteins?
Golgi complex is responsible for processing and sorting proteins from ER to the right destinations by vesicles
What organelle is the power house of cells? How?
Mitochondria which contains its own DNA and replicates by fission makes ATP used as energy currency for cell’s activities
What organelle disposes waste in cells?
Lysosomes are acidic organelles that can break down and dispose waste
What is the function of cytoskeleton?
Cytoskeleton includes filaments and tubules which are responsible for structure, support, and transport
What structure is the plasma membrance?
The plasma membrance is a phospholipid bilayer (hydrophilic heads and hydrophobic tails)
What substances can and cannot move through the plasma membrane?
The plasmas membrane is permeable to non-polar molecules like O2, CO2, H2O, other small uncharged particles.
Impermeable to most essential molecules and ions, small hydrophilic molecules; and maromolecules.
What are diffusion and osmosis?
Diffusion is the movement of substances from higher to lower concentration which happens over time until equilibrium is reached.
Osmosis is water flowing through a semipermeable membrane to another aqueous compartment containing higher solute concentration (follow concentration gradients)
What is tonicity?
The ability of the extracellular solution to make water move into or out of cell to reach equilibrium by osmosis
3 types of tonicity
Isotonic: equal solute concentration –> continous osmosis to maintain equilibrium
Hypertonic: lower solute concentration than outside –> water flow out of cell –> shrink
Hypotonic: higher solute concentration than outside –> water flow into cell –> swell
What are included in the membrance in order to transport bigger molecules?
“Transmembrane” or integral membrane proteins
What are the functions of proteins located within the plasma membrane?
These proteins interact with different stuffs outside and inside the cells as well as forming pores (or channels) for facilitated diffusion and active transport.
What types of molecules or stuffs that require channels to move in and out of the cell?
Ions, proteins, macromolecules
What channels are needed to transport a huge amount of water we take in everyday?
Aquaporins, which appear everywhere in our body, dynamically regulate the amount of water present. These channels help to increase the amount of water taken up.
Explain the differences between facilitated diffusion and active transport
Facilitated diffusion: molecules move from higher to lower concentration without taking up any ATP (follow the concentration gradients)
Active transport: molecules use ATP to move from lower to higher concentration (against the concentration gradients)
What happens when ions pass through transmembrane proteins?
When ions move through the channels, the charge inside and outside of the cell become different, creating electrochemical potential difference. That why we say ions channels conduct charge.
Explain the process of the Sodium-Potassium pump and its functions
The Sodium-Potassium Pump (or Na-KATPase) pumps 3 Na+ out of the cell and 2 K+ in to the cell ==> create a electrochemical gradients (negative membrane potential)
This helps to maintain a stable resting membrane potential, which is essential for many physiological processes and transport.
What is the role of facilitated diffusion in substances movement?
Facilitated diffusion regulated the movement of nutrients (glucose, amino acids, etc.) across membrane
Explain endocytosis and exocytosis
endocytosis: transporting of materials into the cytoplasm using vesicles
exocytosis: transporting of materials out of the cytoplasm using vesicles (substances secretion)
Explain the concept of homeostasis
Body’s tendency to maintain internal consistency by counteracting change
Explain the differences between negative and positive feedback loops
Negative feedback loops: counteract change to maintain equilibrium, return to set points
Positive feedback loops: amplify first stimulus and move further away from the set points
What is the endocrine system?
A slow chemical-based messaging system in which a set of glands secrete hormones directly into the bloodstream. These hormones will travel to all parts of the body, but impact only cells that contain receptors for that hormone.
How many types of glands are there?
2 types
Exocrine glands: glands that have ducts to bring their secretory matter to a surface
Endocrine glands: ductless gland that internally secrete hormones into bloodstream or lymph
What is hormone?
A hormone is a chemical messenger made by glands, which travel in the bloodstream to target organs and trigger a response.
Describe the function of hormones
- Reproduction, growth, development
- Maintenance of internal environment
- Energy production, utilization, storage
What is a ligand and a receptor?
A ligand is a signaling molecule, so all hormones are glands.
A receptor can be found in the cell membrane or inside the cell, to which the hormone binds and trigger a cell process.
Describe the characteristics of a receptor
- High affinity interaction with ligands (tight binding)
- High specificity for ligands (only bind to one specific ligand)
- Have a specific distribution patterns
Desribe the signaling process
A process of responsing to an external stimulus and making decisions regarding cell processes
Describe the differences between water soluable hormones and lipid soluable hormones
Water soluable hormones are peptide hormones and cannot get through the cell membrane, so they have to bind to a membrane receptors which will trigger a signal cascade and amplification.
Lipid soluable hormones can diffuse through membrane, then bind to a receptor inside the cell and change gene expression.
Describe signal amplification
A process in which the first signal activated by first messenger binding the receptor will be relayed and intensifies during intracellular reactions.
Describe phosphorylation cascade
Phosphorylation cascade is a series of signalling events in which one protein after another become phosphorylated and then, activate the targeted protein.
Compare first and second messenger
First messenger: extracellular substances which, through receptor-binding, can trigger intracellular processes
Second messenger: (like intracellular ligands) intracellular substances that bring signals from the receptors to to targeted proteins, mediated by kinases enzymes
What makes a second messenger?
- Has to be low amount in resting state
- Regulated synthesis
- Regulated destruction
- Act through other proteins
Describe steroid hormones and its functions
Steroid hormones are derivatives of cholesterols, so they can enter cell without membrane receptors (but still bind to a hormone receptor inside the cell)
These hormones cause growth (via protein production), regulate endometrial growth and menstruation.
What is an oxytocin?
Oxytocin is hormone involved in uterine contraction and breast milk ejection.
What is ADH?
Antidiuretic hormone which prevents water loss through kidneys
This hormone is released when
- blood osmolarity increases
- blood pressure decreases
- blood volume decreases
