Module 1 and 2 Flashcards
Eukaryotic Cells
Plants and animals cells with a nucleus and membrane - enclosed organelles
Prokaryotic Cells
unicellular organisms, without a nucleus or membrane-enclosed organelles.
Functions of the plasma membrane:
maintains specific conditions for cellular function within the cell. Selectively permeable, therefore plays an important role in entrance and exit of substances. Carries markers that allows cells to recognise one another and can transmit signals to other cells via receptors.
What differentiates bacterial cells?
Bacteria have no true nucleus
Function of the cytoplasm
The interior portion filled with cytosol
Function of Nucleus
Membrane-enclosed internal region that contains genetic material
What are the main structures of the cytoplasm? (8)
Centrioles, cytoskeleton, lysosomes, mitochondria, peroxisomes, golgi apparatus, endoplasmic reticulum and ribosome.
Function of ribosomes and where they are found
Ribosomes are the structures in which protein synthesis takes place. Found inbound in the cytoplasm, attached to the outer side of the nuclear membrane or attached to the ER.
Functions of the endoplasmic reticulum
Delicate membrane structure, contiguous with nuclear membrane. Forms an extensive net of channels, and classified into smooth and rough types.
Function of the rough ER
Lots of ribosomes attatched.
Synthesise and store proteins in ribosomes
Function of smooth ER
No ribosomes.
Functions in diverse metabolic processes
Important for contraction stimuli in muscle cells
Function of Lysosomes
Intracellular digestion through digestive enzymes.
Explain autographic digestion
Occurs when residual substances of the cellular metabolism are digested
Explain heterographic digestion
When substances that enter the cell are digested.
How do lysosomes digest things?
Lysosomes enfold the substances, forming digestive vacuoles or residual vacuole, later fusing with the plasma membrane to release digested material to exterior.
Function of mitochondria and where is it found
Organelles in which the most important part of cellular respiration occurs - ATP production - Krebs cell and the respiratory chain. Numerous in eukaryotic cells, particularly muscle cells. Can self-replicate.
What is cellular respiration?
The process of using an organic molecule (mainly glucose) and oxygen to produce carbon dioxide and energy.
About chloroplasts
organelles in plants in which photosynthesis occurs.
What is photosynthesis?
The production of highly energetic organic molecules (glucose) from carbon dioxide, water and light.
Function of plant cell wall
Structural and protective functions. Important role in limiting cell size and stopping cells from bursting.
Function of vacuoles in plants
Osmotic balance of the intracellular space. Absorb and release water in response to cellular metabolic necessities.
How does DNA use information?
DNA -> cell
DNA -> encodes genes -> encodes proteins
Describe transcription
gene -> protein. Cell produces an intermediate molecule call messenger RNA (mRNA)
Describe translation
Cell uses mRNA to produce protein.
Things in prokaryotes but not eukaryotes
No internal membrane
No nucleus
Naked DNA
Describe cytosol
Semifluid substance within cell
Define chromosomes
Carry genes in the form of DNA
Where does translation take place
Ribosomes
Cellular respiration formula
C6H12O6 + 6O2 = 6CO2 + 6H20 + ATPs
Where in plants is chlorophyll found?
In the plastids
Function of the cytoskeleton
A dynamic set of filaments
For cell shape, support and movement
What do vacuoles contain?
enzymes, ions, pigments and toxic metabolic bby-products
What determines if something diffuses across a membrane?
- concentration gradient
- size
- charge/polarity/uncharged
- hydrophobic more likely to diffuse
Compare passive and active transport
Passive = osmosis, diffusion Active = pumped across the membrane
What molecules can’t diffuse, and how do they cross the membrane?
Na+, Cl-, K+. Must be TRANSPORTED
How are cells identified?
By protein markers. Receptor proteins interact with specific chemicals.
Explain the theory behind the fluid mosaic model
Phospholipids are AMPHIPATHIC molecules.
Membrane is fluid with a ‘mosaic’ of proteins embedded in it
Compare hydrophilic and hydrophobic
Hydrophilic - water loving (head)
hydrophobic - water hating (tail)
What does being amphipathic allow?
Ability to interact with both polar and non-polar substances
What do the energy levels of electrons do?
Partition the electrons into orbitals of different energy levels. Electrons with a higher energy state can sit further away from the nucleus.
Can electrons move from one shell to another?
Yes, but only if the energy it gains or loses is exactly equal to the difference in energy between the energy levels of the two shells.
Write the Aufbau principle
Electrons fill the lowest available energy levels before filling higher levels.
Write the Lazy Tenant Rule
Electrons at higher levels require higher energy to stay away from the nucleus
Write Hund’s Rule
Where there is a choice, electrons fill the orbitals singly as far as possible, to minimise repulsion between electrons.
Whats the difference between the atomic and mass number
Atomic = number of protons Mass = number of protons and neutrons
What are the naturally occuring elements in the human body?
Oxygen, Carbon, Hydrogen and Nitrogen
What is electronegativity?
ability of an atom to attract an electron to itself
What is electropositivity?
Willingness of an atom to give up an electron
How are covalent bonds formed?
Formed when two atoms share one or more pairs of electrons. DON’T LOSE BUT SHARE
How is a polar bond formed?
Molecule formed with electrons that have different electronegativities.
Define polar
One end of the molecule has the electrons near it more frequently.
What are the three weak interactions?
- Ionic bonds
- Hydrogen bonds
- Van der Waals attractions
Describe ionic bonds
CHARGE TO CHARGE INTERACTIONS. Bonding due to force of attraction between a positive and negative ion. Ions formed because sometimes an interaction is more favourable if the valence electrons are completely stripped from one partner and given to the other.
How does water interact with charged ions?
By hydrating them. Water molecules orient themselves around the ions.
Explain Hydrogen bonds
An electrostatic attraction between an electronegative atom (O, N, F) and a Hydrogen atom attached to an electronegative atom.
Explain Van der Waals attractions
Instantaneous induced dipole - induced dipole. Occur over a very small and very defined distance. Not dependent on ionization or covalent bonding. The key is the oscillations of electrons around adjacent atoms.
What does the structure of water allow it to do?
Polar covalent bonds result in H bonding. Water is cohesive, and can act as a buffer. It can moderate temperature - the solvent of life.
Explain why/how water is a cohesive suubstance
3D networks of Hydrogen bonding in water holds molecules together making it a cohesive (sticky) substance.
How does water have high specific heat capacity?
The Hydrogen bonds are constantly being broken and reformed, making it resistant to heat change
Compare solution v solvent v solute.
A liquid that is a completely homogenous mixture of two or more substances is a solution.
The dissolving agent is the solvent.
The substance that is dissolved is the solute.
Why can polar and charged molecules dissolve in water?
Because they can interact with each other through polar bonding and other charge - charge interactions.
What will and won’t dissolve in water.
WILL: polar molecules e.g. protein
WON’T: non-polar molecules e.g. lipids
Avogadro’s number
6.023 x 10^23
What happens to water when it dissociates (i.e. covalent partnerships are disrupted)
Results in hydronium ions and hydroxide ions
How is the acidity of a solution measured?
By the concentration of H3O+ ions present.
Higher the pH - lower the concentration of H3O+
Lower the pH - lower the concentration of H+
Explain the carbonic-bicarbonate system
Major buffer system in the body. CO2 is carried to the lungs for elimination or is dissolved in body fluids - forming carbonic acid (H2CO3) that dissociates, the the freed proton reassociates with water to produce bicarbonate ions (HCO3–) and Hydronium ions (H3O+).
Write the equation for the carbonic - bicarbonate system
H2CO3 + H2O HCO3- + HCO3+
What does the buffer system do with protons?
Soaks them up and locks them into a relatively stable compound.
What is molarity versus moles
Molarity is an expression of concentration, whilst moles indicate absolute numbers of molecules.
How do acid and bases relate to protons?
Acids are proton donors and a base is a proton acceptor.
Characteristics of proteins
Lots of nitrogen, not phosphorous
Characteristics of carbohydrates
Hydrated carbons - i.e. with things that make water (H & O)