life at the cellular level Flashcards
Describe the features of prokaryotic cells vs eukaryotic cells.
Prokaryotic cells: no nuclear membrane, no mitochondria and no membrane bound organelles. Eukaryotic cells: multicellular animals and plants, membrane bound organelles and nucleus.
What does facilitated diffusion require?
Carrier molecules.
What are the 4 types of junctions in cells?
1) Tight/occulding junctions - prevent extracellular constituents getting inside the cell. 2) Adhesive - link actin filaments of 2 different cells. 3) Desmosomes: link keratin filaments in 2 different cells. 4) Gap: channels linking 2 cell cytoplasms together for communication eg. heart muscle.
What is the difference between pancrine and endocrine?
Pancrine: target cell is close to signalling cell. Endocrine: effects can be further away
What type of DNA do mitochondria have?
Their own circular DNA. They self-replicate, have their own ribosomes and make most of their own proteins.
What is the difference between heterochromatin and euchromatin?
Heterochromatin stains darker as it is tightly packaged and is in cells that are less active. Euchromatin is in cells that are active in transcription and stains lighter.
What is the function of the smooth ER?
To break down compounds like drugs and glycogen or to synthesise compounds like lipids.
What are the 3 molecules that make up the cytoskeleton?
Microfilaments (smallest, make up strands of actin), intermediate filaments (fibrous) and microtubules (long strands of alpha and beta tubulin).
What is 99% of us made of and why?
H, N, O and C as they form the strongest bonds. C is the most versatile and forms the basis of all biomolecules.
Define conformation and configuration.
Conformation: the arrangement of atoms in a molecule that can move without breaking H bonds. Configuration: fixed arrangement of atoms in a molecule.
Give an example of alterations to cis and trans conformation.
Rhodopsin in the retina is made from retinal and opsin. Retinal is in cis conformation and light converts it to trans.
Are biological molecules in L or D conformation?
All are in L.
What are the 5 chemical reactions of life?
1) Redox: H transfered in glycolysis and NAD+ becomes NADH. 2) Making/breaking C-C bonds: cleavage of glucose in glycolysis to release some of its potential energy. 3) Internal rearrangements: G6P –> F6P. 4) Group transfers: F6P to F6bP. 5) Condensation and hydrolysis: molecules are joined by condensation and broken by hydrolysis. Condensation reactions make water and hydrolysis reactions use water to split compounds.
How many bonds are in A-T vs C-G?
A-T has 2 bonds and C-G has 3 bonds.
Describe the structure of glucose polymers.
Formed by condensation reactions between glucose monomers. Lots of monomers liked together? Locked in cyclic form except the end monomer which remains linear and forms a reducing end.
What is the first law of thermodynamics?
Energy can be converted from 1 form to another, but the total energy in the universe remains constant.