Chapter 3: Cells Flashcards
Structure dictates _____
function
What is the meaning of the word “eukaryote”?
“true nut”
What do prokaryotic cells lack?
Nucleus
What type of cells are human cells?
Eukaryotes
Cytoplasm
All liquid within the cell that’s not in the nucleus
What is present inside organelles?
Cytoplasm
Cytosol
The liquid portion inside the cell that’s NOT inside any organelles
What are the functions of a membrane?
-controls passage of substances
-detects chemical messengers
-links adjacent cells
-anchors cells to extracellular matrix
What is the composition of a membrane?
Phospholipid bilayer
What are the three notable properties of a membrane?
-nonpolar
-fluid mosaic
-selectively permeable
Integral proteins
Embeds in a membrane
Transmembrane proteins
integral protein that goes all the way through a membrane
What is the function of a transmembrane protein?
Creates ion channels
Peripheral proteins
Not embedded withing the structure of the membrane
What is the function of a peripheral protein?
Helps with cellular communication
What components are imbedded in the phospholipid bilayer?
-glycoproteins for cell recognition
-cholesterol hold cell layer together
Junctions
Where cells come together
Integrins
Transmembrane proteins that connect cells
Desmosome
region between two adjacent cells held together by proteins
Cadherins
The proteins extending into extracellular space
Where are cadherins found?
Epithelial tissue
Tight junction
When two cells come together tightly; creates a tissue barrier
Gap junction
two cells connected by a protein; allows for quick information transfer
Nucleus
Stores and protects genetic information (DNA)
Nuclear envelope
Tightly controlled phospholipid bilayers
Nuclear pores
proteins that allow certain substances across two membranes
What specific molecule moves through nuclear pores?
RNA
Nucleolus
Synthesizes ribosomes
Ribosomes
Synthesizes proteins
What does RNA bind with to carry out reactions?
Ribosomes
ER
endoplasmic reticulum
Rough ER
involved in protein synthesis due to heavy amount of ribosomes
Smooth ER
Synthesizes lipids, stores calcium
Golgi apparatus
Postal service of the cell; protein modification
Secretory vesicle
-Golgi
-Sends things outside of the cell
Mitochondria
Produces ATP
Hierarchy of mitochondrial layers
-outer membrane
-intermembrane space
-inner membrane
-matrix
What are the folds in the inner membrane of the mitochondria called?
Cristae
Lysosomes
contains digestive enzymes; breaks down things the cell eats
Peroxisomes
-breaks down hydrogen peroxide
-lipid metabolism, which generates more ATP
Cytoskeleton
provides structure and support for the cell
Actin filaments
-composition
-addition?
-function
-G-actin (golbular)
-can easily be broken down or added to
-helps cells move
Intermediate filaments
-composition
-addition?
-function
-composed of desmin
-cannot be easily broken down
-provides structural support
Microtubules
-compositon
-addition?
-function
-composed of tubulin
-can easliy by broken down/added to
-movement within the cell
Centrioles
guide mitosis
Central Dogma
DNA –transcription–> RNA –translation–> Protein
Transcription Factors
Control the transcription of central dogma
(DNA –> RNA)
Protein Degradation
Proteins break down/become denatured over time
Ubiquitin
Special protein that tags damaged proteins and brings them to a proteasome
Proteasome
Special protein that unfolds the damaged protein into small peptides
(garbage disposal of cell)
Ligand
Any molecule that binds to a protein
Binding Site
The region of a protein that a ligand binds to
What happens to a protein when it is bound to a ligand?
It’s conformation changes
Chemical Specificity
Whether or not a binding site CAN bind to a certain ligand or not
Chemical Affinity
How strongly a ligand binds to a protein
Specificity is dependent on _____, while affinity is dependent on _____.
Shape; charge
Saturation
How many of the total binding sites are occupied
What occurs to a protein when it is fully saturated?
The reaction the protein is involved in occurs as fast as possible
Allosteric modulation
When one binding site at a protein is bound to a ligand, which changes the shape of another binding site
Functional Site
Carries out the protein’s physiological function
Regulatory Site
The other site on a protein that, when bound to a moldulator molecule (ligand), changes the shape and function of the functional site
Modulator molecule
Binds to the regulatory site and changes the shape and function of the regulatory site
Covalent modulation
Actual bonds shared between protein and ligand
Phosphorylation
Covalent modulation in which a phosphate group is added
Kinase
Mediates protein phosphorylation
Phosphatase
Removes a phosphate
Catabolism
The breaking down of organic molecules
Anabolism
The synthesis of organic molecules
Chemical bonds
Shared electrons
Forming a bond requires __________
An input of energy
What are the four determinants of reaction rates?
-concentration
-activation energy
-temperature
-catalyst
Law of Mass Action
the direction of a chemical reaction is determined by the concentrations of reactants and products
(based on reversible reactions)
Enzymes
Protein Catalyst
Substrate
Ligand
Lock and Key model
Substrates fit perfectly into the enzyme
Induced fit model
Substrates change the shape of the active site in order to fit
What is the main function of an enzyme?
Changes the rate of chemical reaction; does not undergo a reaction
Cofactors/coenzymes
Metal Ions or vitamin derivatives that participate in the reaction as a substrate
Common cofactors
NAD+, FAD
What is the function of a coenzyme?
Helps carry molecules from one substrate to another; vital in the occurrence of a reaction
What three factors are enzyme-mediated reactions regulated by?
-substrate concentration
-enzyme concentration
-enzyme activity
Metabolic pathways
Basis of cellular metabolism; breaks down molecules to form necessary cellular products
Which form of feedback do metabolic pathways often use?
Negative feedback loop
Allosteric inhibitor
Something that binds to the enzyme other than the active site and turns off the pathway
Examples of metabolic pathways
-hydrolysis of ATP
-glycolysis
-Krebs cycle
-oxidative phosporylation
Hydrolysis of ATP
Form of metabolism where the terminal phosphate group is removed from ATP and energy is released
Glycolosis
-takes place in the cytosol of the cell
-end product: pyruvate
-per glucose molecule: 2 NADH, 2 ATP, 2 pyruvate
Krebs Cycle
Fate of pyruvate if oxygen is present
Where does the Krebs Cycle occur?
Mitochondrial Matrix
The Krebs Cycle results in what product?
The most amount of reduced coenzyme (acetyl-Co A)
Lactic Acid pathway
-fate of pyruvate if no oxygen is present
-repeats glycolysis quickly
Reduced coenzymes
-NADH
-FADH2
Substrate level phosphorylation
GTP
(high energy molecule made of guanine)
For every TWO molecules of glucose that enter the Krebs cycle:
-6 NADH
-2 FADH2
-4 CO2 (waste)
-2 ATP/ GTP
For every ONE molecule of glucose entering glycolysis:
-2 NADH
-2 ATP
-2 pyruvate
Chemiosmosis
Moves ions across a semipermeable membrane from high to low concentration
Oxidative phosphorylation
Uses H+ ions and an electron transport chain to pump electrons through a protein complex to synthesize ATP
What is the final electron acceptor in the electron transport chain of oxidative phosphorylation?
Oxygen
What is the waste product of oxidative phosphoprylation?
Metabolic water
Three main metabolic processes and their functions
-Glycolysis: generates pyruvate
-Krebs cycle: generates lots of reduced coenzyme
-Oxidative phosphorylation: releases ATP
