Biology 190 exam 2

Structure of the cell membrane

The plasma membrane is a fluid mosaic. This means that it is flexible and made up of many different types of molecules. Phospholipids form the basic structure of a cell membrane, called the lipid bilayer. Scattered in the lipid bilayer are cholesterol molecules, which help to keep the membrane fluid consistent.

Fluid mosaic model

describes the plasma membrane as a fluid combination of phospholipids, cholesterol, and proteins.

Lipid bilayer

The lipid bilayer is a universal component of all cell membranes. Its role is critical because its structural components provide the barrier that marks the boundaries of a cell. The structure is called a "lipid bilayer" because it is composed of two layers of fat cells organized in two sheets.

Selectively permeable

A selectively permeable cell membrane is one that allows certain molecules or ions to pass through it by means of active or passive transport.

Phospholipid

Phospholipids are a class of lipids that are a major component of all cell membranes. They can form lipid bilayers because of their amphiphilic characteristic. The structure of the phospholipid molecule generally consists of two hydrophobic fatty acid "tails" and a hydrophilic "head" consisting of a phosphate group.

Integral proteins

type of membrane protein that is permanently attached to the biological membrane.

Peripheral proteins

membrane proteins that adhere only temporarily to the biological membrane with which they are associated.

Channel proteins

a protein that allows the transport of specific substances across a cell membrane.

Carrier protein

Carrier proteins are integral membrane proteins; that is, they exist within and span the membrane across which they transport substances.

Cholesterol

is defined as a lipid, which is a fatty substance that is necessary in your body.

Carbohydrates

any of various neutral compounds of carbon, hydrogen, and oxygen (as sugars, starches, and celluloses) most of which are formed by green plants and which constitute a major class of animal foods.

How does homeostasis relate to plasma membrane?

Cellular homeostasis involves maintaining a balance of several factors that make a cell healthy. The cell membrane is a lipid bilayer that prevents that passage of water and ions. This allows cells to maintain a higher concentration of sodium ions out the outside of the cell.

List 7 functions of the plasma membrane

surrounds the cell, contains the organelles, protects and separates the inside of the cell from the outside, allows and controls the passage of substances in/out of the cell

What does cholesterol have to do with temperature and the plasma membrane?

Cholesterol acts as a bidirectional regulator of membrane fluidity because at high temperatures, it stabilizes the membrane and raises its melting point, whereas at low temperatures it intercalates between the phospholipids and prevents them from clustering together and stiffening.

6 functions of membrane proteins

6 Functions of Membrane Proteins.

Transport. Hydrophilic channel.

Enzymatic activity. Sequential steps in metabolic pathway.

Signal transduction. relay chemical messages.

Intercellular Joining. Various Cell Junctions.

Cell-cell recognition. ...

Attachment to the cytoskeleton and the ECM.

Explain membrane permeability in terms of hydrophobic and hydrophilic

membrane permeability increases with hydrophobicity

What is the difference between active and passive processes of cellular transport?

Passive transport doesn't require energy (ATP), active transport does require energy. Passive transport moves molecules WITH the concentration gradient (high to low), while active transport moves molecules AGAINST the concentration gradient (Low to High).

Types of active transport

The Sodium-Potassium pump, Exocytosis, and Endocytosis.

Types of passive transport

Diffusion, Osmosis and Facilitated Diffusion

Diffusion

is the net passive movement of particles (atoms, ions or molecules) from a region in which they are in higher concentration to regions of lower concentration.

How does concentration gradient affect diffusion?

The concentration gradient determines the direction of movement for particles undergoing diffusion.

How does temperature affect diffusion?

Higher temperatures mean that diffusion will take place more quickly.

How does the mass of a diffusing substance affect diffusion?

The mass of molecules is a major factor, because smaller molecules have higher random velocity for a given ambient temperature, and higher random velocities correspond to faster diffusion.

How does the surface area affect diffusion?

as the surface area increases, more particles can spread as there is more area to travel

How does the diffusion distance affect diffusion?

Rate of diffusion increases when distance decrease.

Osmosis

a process by which molecules of a solvent tend to pass through a semipermeable membrane from a less concentrated solution into a more concentrated one, thus equalizing the concentrations on each side of the membrane.

Aquaporins

are integral membrane proteins that serve as channels in the transfer of water, and in some cases, small solutes across the membrane.

Hydrostatic pressure

The pressure exerted by a fluid at equilibrium at a given point within the fluid, due to the force of gravity.

Explain water balance in a animal cell

Animal cells diffuse water across the plasma membrane through osmosis based on concentration.

Therefore, animals cells maintain the proper balance of water and solutes.

What is the difference between simple and facilitated diffusion?

In simple diffusion, molecules move down the concentration gradient but in facilitated diffusion molecules move up the concentration gradient. Simple diffusion is passive but facilitated diffusion is an active process that uses energy.

Active transport

is the movement of molecules across a cell membrane from a region of their lower concentration to a region of their higher concentration—in the direction against some gradient or other obstructing factor (often a concentration gradient).

How is primary active transport different from secondary active transport?

Primary active transport, also called direct active transport, directly uses metabolic energy to transport molecules across a membrane. In secondary active transport, also known as coupled transport or co-transport, energy is used to transport molecules across a membrane; however, in contrast to primary active transport, there is no direct coupling of ATP; instead it relies upon the electrochemical potential difference created by pumping ions in/out of the cell

Electrochemical gradient

is a gradient of electrochemical potential, usually for an ion that can move across a membrane.

Explain how an electrogenic pump creates voltage across a membrane, and name two electrogenic pumps

By pumping electrons across the membrane leaving one side more positive and making one side more negative which results in a voltage charge

Active transport and sodium-potassium pump

KNOW HOW THE SODIUM-POTASSIUM PUMP (NA+/K+ ATP base) AND PROTON PUMPS WORK AND WHAT THEIR FUNCTION IS.

The process of moving sodium and potassium ions across the cell membrance is an active transport process involving the hydrolysis of ATP to provide the necessary energy.

HOW WILL IT CHANGE THE MEMBRANE POTENTIAL (LOOK AT THE ICONIC CHARGES OF NA+ AND K+ AND THE NUMBER OF THE IONS "PUMPED" EACH CYCLE).

Sodium and potassium ions are pumped in opposite directions across the membrane building up a chemical and electrical gradient for each. These gradients can be used to drive other transport processes.

Secondary (cotransport) transport

Secondary active transport, is transport of molecules across the cell membrane utilizing energy in other forms than ATP.

Vesicular transport

is a membrane protein that regulates or facilitates the movement of specific molecules across a vesicle's membrane.

Endocytosis

the taking in of matter by a living cell by invagination of its membrane to form a vacuole.

Exocytosis

a process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane.

Explain the cyclicial relationship between photosynthesis and cellular respiration

Photosynthesis makes the glucose that is used in cellular respiration to make ATP.

How do we get energy from ATP?

The ATP molecule can store energy in the form of a high energy phosphate bond joining the terminal phosphate group to the rest of the molecule.

Phosphorylation

is the addition of a phosphoryl group (PO3)− to a molecule.

Oxidative phosphorylation

the metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing energy which is used to reform ATP.

Redox reactions

is a chemical reaction in which the oxidation states of atoms are changed.

Be able to name the electron carriers used in cellular respiration and how they function

NAD and FAD

NAD+ picks up an electron from glucose, at which point it becomes NADH. Then NADH will ultimately transport the electrons to the mitochondria, where the cell can harvest energy stored in the electrons.

FAD can temporarily store energy during cellular respiration via a reduction reaction. When FAD reacts with two hydrogen atoms, it can form FADH2.

*********BE ABLE TO NAME AND EXPLAIN THE STEPS IN AEROBIC CELLULAR RESPIRATION. KNOW THE INPUTS AND OUTPUTS OF EACH PART OF THE PROCESS. KNOW WHERE THE STAGES OCCUR*********

Glycolysis

The first step in aerobic respiration is glycolysis, which literally means the breakdown of glucose.

Acetyl-CoA

The next step in aerobic respiration is the formation of acetyl-coenzyme A.

Krebs Cycle

Takes place in your mitochondria. The acetyl-coA that was produced from pyruvate combines during the Krebs cycle to produce oxaloacetate, thus forming citrate.

Electron Transport Chain

This last step uses the NADH and FADH2 that were created in previous steps to generate ATP.

Citric acid cycle

generate larger numbers of carried electrons for oxidative phosphorylation

Fermentation (lactic acid & alcohol)

When in an anaerobic environment, some cells can use glycolysis and fermentation to keep producing ATP. Lactic acid fermentation happens in our muscle cells when we are exercising feverishly, while alcoholic fermentation is used in yeast cells and is what leads to beer, bread, and wine.

Anaerobic respiration

is a type of respiration that does not use oxygen.

Similarities and differences between:

fermentation, anaerobic respiration, and cellular respiration

instead of just ending with the product of glycolysis like fermentation does, anaerobic respiration will create pyruvate and then continue on the same path as aerobic respiration.

Bioenergetics

concerns energy flow through living systems.

Energy

The ability to do work. Objects can have energy by virtue of their motion (kinetic energy), by virtue of their position (potential energy), or by virtue of their mass (see E = mc2).

2 major forms of energy

kinetic and potential

Energy exist as..

potential and kinetic

Endergonic

absorb energy from the surroundings.

Exogenic

release energy to the surroundings.

Metabolism

the chemical processes that occur within a living organism in order to maintain life

Anabolic pathways for metabolism and equation

Anabolic pathways then build new molecules out of the products of catabolism, and these pathways typically use energy. The new molecules built via anabolic pathways (macromolecules) are useful for building cell structures and maintaining the cell.

Catabolic pathways for metabolism and equation

Catabolic pathways involve the breakdown of nutrient molecules (Food: A, B, C) into usable forms (building blocks). In this process, energy is either stored in energy molecules for later use, or released as heat.

ATP

Adenosine triphosphate (ATP) is considered by biologists to be the energy currency of life.

Chemical structure of ATP

C10H16N5O13P3

What is the role of ATP?

ATP is a nucleotide that performs many essential roles in the cell. It is the major energy currency of the cell, providing the energy for most of the energy-consuming activities of the cell.

Know how ATP works

It transports the energy obtained from food, or photosynthesis, to cells where it powers cellular metabolism.

ATP works in coupled reactions. Explain

an energetically favorable reaction (like ATP hydrolysis) is directly linked with an energetically unfavorable (endergonic) reaction

Enzymes

macromolecular biological catalysts

Role of enzymes

Enzymes are very efficient catalysts for biochemical reactions. They speed up reactions by providing an alternative reaction pathway of lower activation energy.

How do enzymes function?

in tightly regulated pathways that are controlled by genes

Enzymes are..

specific to what they catalyze

What is Ea?

Activation energy is the minimum amount of energy required to initiate a reaction.

How do enzymes affect Ea?

Enzymes decrease the Gibbs free energy of activation, but they have no effect on the free energy of reaction.

Enzyme-substrate complex

The intermediate formed when a substrate molecule interacts with the active site of an enzyme.

3 conditions that affect enzyme activity

temperature, pH, enzyme concentration, substrate concentration, and the presence of any inhibitors or activators.

How do enzyme inhibitors work?

An enzyme inhibitor is a molecule that binds to an enzyme and decreases its activity.

Name and describe the two types of enzyme regulators/inhibitors

Cofactors, mostly metal ions or coenzymes, are inorganic and organic chemicals that assist enzymes during the catalysis of reactions. Coenzymes are non-protein organic molecules that are mostly derivatives of vitamins soluble in water by phosphorylation; they bind apoenzyme to proteins to produce an active holoenzyme.

Feedback inhibition

a molecule that binds to an enzyme and decreases its activity.

Heterotroph

is an organism that cannot fix carbon from inorganic sources but uses organic carbon for growth

Autotroph

is an organism that produces complex organic compounds from simple substances present in its surroundings, generally using energy from light or inorganic chemical reactions

Equation for photosynthesis

carbon dioxide + water —> glucose + oxygen + water

6CO2 + 6H2O —> C6H12O6 + 6O2

Photosynthesis inputs and outputs

Inputs- light energy, and matter in the form of water absorbed through the roots, and carbon dioxide absorbed through the leaves

Outputs- oxygen, which is released into the air, and glucose sugar (chemical energy), which is used to keep the plant aliv

Photosynthesis is

endergonic and anabolic

Light and Calvin (dark) reactions for photosynthesis

Light reactions need light to produce organic energy molecules (ATP and NADPH). They are initiated by colored pigments, mainly green colored chlorophylls.

Dark reactions make use of these organic energy molecules (ATP and NADPH). This reaction cycle is also called Calvin Benison Cycle, and it occurs in the stroma. ATP provides the energy while NADPH provides the electrons required to fix the CO2(carbon dioxide) into carbohydrates.

Know where they occur for light and Calvin (dark) reactions for photosynthesis occur

The "light-independent" or dark reactions happen in the stroma of the chloroplasts.

The energy carriers for light and Calvin (dark) reactions for photosynthesis

ATP and NADPH

Know 3 steps of Calvin cycle

Carbon fixation

Reduction

Regeneration

What makes fall colors?

Chlorophyll

Chemiosmosis is the same as..

electron transport chain

Compare mitochondria (cellular respiration) and chloroplast (photosynthesis)

Mitochondria are the "powerhouses" of the cell, breaking down fuel molecules and capturing energy in cellular respiration.

Chloroplasts are found in plants and algae. They're responsible for capturing light energy to make sugars in photosynthesis.

3 stages of cell signaling

1. Reception

2. Transduction

3. Response

3 main types of membrane receptors involved in reception

GPCRs, RTKs, ligand-gated ion channel receptors

Role of protein kinases and phosphatases in signal transduction (shape changes)

Protein kinases and phosphatases are enzymes catalysing the transfer of phosphate between their substrates. A protein kinase catalyses the transfer of -phosphate from ATP (or GTP) to its protein substrates while a protein phosphatase catalyses the transfer of the phosphate from a phosphoprotein to a water molecule.

Role of a phosphorylation cascade in signal transduction

A phosphorylation cascade is a sequence of events where one enzyme phosphorylates another, causing a chain reaction leading to the phosphorylation of thousands of proteins. This can be seen in signal transduction of hormone messages.

Difference between first and second messengers

First messenger is the ligand, second messenger is any small, non-protein components of a signal transduction pathway.

List 4 second messengers

cyclic nucleotides (e.g., cAMP and cGMP)

inositol trisphosphate (IP3)

diacylglycerol (DAG)

calcium ions (Ca2+)

Role of transcription factors in nuclear responses

controls the rate of transcription of genetic information from DNA to messenger RNA, by binding to a specific DNA sequence

How do enzyme cascades amplify the cell's response

At each catalytic step in the cascade, the number of activated products is much greater than in the preceding step

Role of scaffolding proteins in forming signaling complexes

they bring multiple binding partners together to facilitate their concerted interactions and functions

What is cancer?

A disease in which abnormal cells divide uncontrollably and destroy body tissue.

What is cell division named?

mitosis and meiosis

Why do cells need to divide?

Cells are limited in size because the outside (the cell membrane) must transport the food and oxygen to the parts inside. As a cell gets bigger, the outside is unable to keep up with the inside, because the inside grows a faster rate than the outside.