Biology 1010 2 Flashcards
What is a cell?
The Basic Unit of life; smallest unit of life
What was the contribution of Leeuwenhoek
One of the first people to observe single celled organisms
What was the contribution of Hooke?
coined the term “cell”
What was the contribution of Schleiden?
Said all plants are composed of cells
What was the contribution of Schwann?
Said all animals are composed of cells
What was the contribution of Brown?
First person to observe the nucleus of an atom
What was the contribution of Virchow?
Said all cells come from pre-excisting cells.
What is cell theory?
The cell is the basic unit of life and that all living organisms are made up of one or more cells
what is the plasma membrane?
All cells have one, it separates the inner contents of the cell from the outer environment and regulates the passage of molecules and ions in and out of the cell.
What is the cell wall?
Not all cells have one, ( animal cells dont). it provides structural support for the cell.
What is cytoplasm?
A semifluid protion of the cell that lies outside the nuclues and inside the plasma membrane. Also contains organelles.
What is Cytosol?
The semi-fluid portion of the cytoplasm ( does NOT have organelles)
What are Eukaryotic cells?
DO have a membrane bound nucleus, contained in animals, plants and fungi
DNA- separated from the rest of the cell inside the nucleus
What are Prokaryotic cells?
Do NOT have a membrane bound nucleus
DNA- in the nucleotide region and is in contact with the cytoplasm of the cell.
What are the characteristics of phospholipid molecules that make them suitable for forming plasma membranes?
Ideal for forming plasma membranes because they have polar heads that orient toward the watery cytoplasm on the inside of the cell.
Describe the fluid mosaic model of the plasma ( cell) membrane.
protein molecules form a shifting pattern within the fluid phospholipid bilayer cholesterol lends support to the membrane
what is the function of the extracellular matrix in animal cells?
Do not have cell walls; but they do have a plasma membrane that has protective and supportive functions.
what is the function of the extracellular matrix in plant cells?
the cell was protects the cells inside and makes sure that they dont obtain too much water, so they dont burst, and also maintains their shape
what is the function of Desmosomes/ Adhesion Junctions?
act like rivets that mechanically connect adjacent cells ( found in skin cells)
What is the function of tight junctions?
form barriers with the external environment ( found in kidneys and digestive system)
What are the functions of gap junctions?
Allow for communication between cells ( Ions and other small molecules can pass back and forth between cells) in plants are called PLASMODESMATA
What are the functions of the nucleus?
the control center of the cell, contains DNA, directs the activities of the cell.
What is the function of the nuclear envelope?
separates the contents of the nucleus from the cytoplasm
What is the function of chromatin?
the non condensed form of DNA
What is the function of ribosomes and where are they located ?
small round organelles made of protein and RNA; function in protein synthesis. found in the cytoplasm of the cell.
What is the nucleolus?
where the components of ribosomes are made
How does DNA direct protein production?
mRNA ( messenger RNAs) copies a genetic “ recipe” from a gene on DNA in the nucleus, then mRNA carries the genetic “ recipe” from the nucleus out into the cytoplasm, ribosomes then move along the length of mRNA decoding the message into a protein product
What is the structure and function of endoplasmic reticulum?
The structure is membranous flattened channels and tubular canals; functions as a transport system
Rough ER?
studded with ribosomes and functions in processing proteins
Smooth ER
lacks ribosomes and specializes in lipid synthesis molecules moving through the endoplasmic reticulum and eventually enclose in vesicles that move to the Golgi apparatus.
What is the structure and function of the Golgi apparatus?
stack of membranous saccules; functions in processing, packaging, and distributing cell products
What is the structure and function of Lybosomes?
function: Intracellular digestion
Structure: membranous vesicles containing digestive enzymes
What is the structure and function of Vacuoles?
membrane bound sacs used for storage and transport
what is a central vacuole and where is it found?
They hold a lot of water and are found in plant cells.
What is the structure and function of chloroplasts?
its a double membrane bound organelle with a 3rd membrane inside the first two, contain thylakoids stacked into grana
Function: photosynthesis
What is the structure and function of mitochondria?
structure: double-membrane bound organelle, inner membrane is folded inward to form cristate that project into the matrix.
Function: Cellular respiration and the production of ATP molequles.
What is the structure and function of cytoskeleton?
structure: network of microtubules extending throughout the cytoplasm
function: maintains cells shape and assists in movement of cell parts.
What is the structure and function of microtubules?
Structure: Cylinders of protein molecules present in the cytoplasm, cilia and flagella.
function: maintains cells shape and assists in movement of cell parts.
List the similarities and differences between flagella and cilia
Similarities: Functions in the movement of the cell
Differences: Flagella is one or a few long extensions from some cells and cilia is several short extensions from cells.
What is energy?
The capacity or ability to do work.
What are the forms of energy?
- mechanical ( kinetic)
-chemical ( potential)
-electrical - light
- heat
What kind of energy is utilized by the cells?
Chemical energy. ( as well as heat?)
Compare kinetic energy with potential energy
Kinetic energy: energy of motion
Potential energy: stored energy
Cells use energy to do what?
- generates metabolic reactions
-transports all required substances through membranes
-helps perform mechanical works, inclusive of moving muscles
Explain the 1st Law of thermodynamics
Energy can neither be created nor destroyed, only change from one form to another.
Explain the 2nd law of thermodynamics
energy transformations are not 100% efficient. There will always be some energy released as heat
What is the primary source of energy for all living organisms?
The sun.
What is entropy?
A measure of the disorganization in a system. it takes a constant supply of energy to combat entropy. heat has the most entropy because it is disorganized.
What is meant by a one way flow of energy?
sun-plants-heerbivores-carnivores-top conivores
energy cannot be recycled
What is metabolism?
All the chemical reactions that place within cells during growth and repair
what is the difference between a calorie and Calorie
calorie: a small calorie
Calorie: a large Calorie ( a kilocalorie) found on food packages
Describe 3 components of the ATP molecule
- nitrogenous base adenine
- sugar ribose
- three phosphate groups
What is the function of ATP?
- chemical work: synthesis of macromolecules
-transport work: pumping of substances across plasma membranes - mechanical work: muscle contraction, beating of cilia and flagella, chromosome movement during cell devision.
What is phosphorylation?
to add a phosphate group to a molecule
What is the significance of the ATP/ ADP cycle?
when ATP is used for energy by cells, the 3rd phosphate group is removed, so with this bond broken, ADP and inorganic phosphate remain. We can get by with a very small amount of ATP even though we use the equivalent of hundreds of pounds of ATP per day. ATP is continually recelyled from ADP and phosphate.
What is an enzyme?
organic catalysts ( usually globular proteins) that speed up chemical reactions without themselves being permanently changed.
What 4 features do enzymes have in common?
1: Enzymes don’t make a reaction happen that couldn’t happen on its own .
2: Enzymes are not permanently altered or used up in reactions. they can be used over and over again
3. The same enzyme works in both the forward and reverse directions of a reaction.
4. Sensitivity to heat and PH.
Define:
Active site and allosteric site.
Active site: the place on an enzyme where the substrates fit
Allosteric site: any place on the enzyme that is not the active site.
Define Activation energy, how is it altered when enzymes are present?
Activation energy: Energy that must be added to cause molecules to react with one another.
Enzymes lower the activation energy so that molecules react more easily.
How do temperature and PH effect enzyme activity?
they can be denatured by heat and change in PH
What is feedback inhibition? And how is it important in metabolic pathways?
(a form of negative feedback) The product being produced binds with the enzyme (at the active site or a allosteric site) and prevents substrate from
binding. This shuts the process down for a time until the product is used up.This keeps the concentration of product within a certain
range.
What is Negative feedback?
decrease in function in
response to a stimulus. Negative feedback shuts down or slows down processes temporarily. Examples: body temperature regulation, blood pressure,
What is positive feedback?
an increase in function in response to a stimulus. Positive feedback encourages processes to continue or proceed
more rapidly. Examples: blood clotting, uterine contractions during labor, milk letdown.
What is the function of phospholipids in the membrane?
forms the matrix of the membrane
* acts as a hydrophobic, impermeable
barrier that prevents the movement of polar (most biological) molecules through the plasma membrane
What is competitive inhibition?
when another molecule
with a very similar shape to that of the
enzyme’s substrate or some of the product just produced binds with the enzyme at its active site. As long as the active site is plugged up, no new product is produced.
What is noncompetitive inhibition?
when some inhibitory or regulatory molecule binds with an enzyme’s allosteric site. This changes the
shape of the active site so that no substrate can fit and this prevents product from being formed
What is the function of the protein component of the membrane?
carries out most of the functions of the
plasma membrane
* proteins can move laterally (from side to side, not up and down) in the fluid bilayer
What are channel proteins?
have a tunnel for ions and small molecules to cross the membrane.
What are carrier proteins?
Also have a tunnel or channel, but they temporarily bind/bond with larger, bulkier molecules ( such as glucose) to help them across the membrane.
What are Cell Recognition proteins
These proteins have branched carbohydrate chains attached that identify the cell as “ self” rather than “non-self”
What are Receptor proteins?
These proteins have carbohydrate chains that form a receptor for molecules such as hormones. When a hormone or other regulatory molecule fits
into the proper receptor, this causes a change in the function of the cell
What are Enzymatic proteins?
These are enzymes that circulate in the cytoplasm, issue fluid, and blood. Enzymes speed up chemical reactions.
What are Adhesion proteins?
Anchor neighboring cells together. These are the desmosomes
What’s selectively permeable?
The passage of most molecules into and out of the cell is regulated
What is Diffusion?
random movement of molecules from an area of higher concentration to an area of lower concentration until they are equally distributed. (Diffusion is a passive process. This means no energy is required to make it happen.)
What is osmosis?
movement of water across a
selectively permeable membrane. Water will move from where water is more
concentrated to where water is less concentrated. Another way to think about this is to realize that water will move toward
greater solute concentration. (“Wherever the salt is, the water will follow.”)
What is Osmotic Pressure?
results when water flows
across a membrane to an area where there is greater solute concentration. This exerts
pressure on the membrane.
What is Turgor Pressure?
related to osmotic pressure.
As plant cells gain water, the water pushes out against the cell walls. This gives internal support to cells and allows the plant to stand upright.
Isotonic?
same concentration of water and non-diffusible solutes on both sides of the plasma membrane
Hypotonic?
dilute solutions meaning that the concentration of water is higher than inside
the cells and the concentration of solutes is lower than inside the cells
Hypertonic?
concentrated solutions meaning
that the concentration of water is lower than in the cells and the concentration of solute
is higher than inside the cells
What is Facilitated transport?
Molecules are transported across the plasma membrane from the side of higher concentration to the side of lower concentration. This is a passive process and does not require energy.
What is Active Transport?
molecules move across plasma membranes from an area of lower to an area of higher concentration with the help of a carrier. This process requires a lot of energy because molecules are moving against the concentration gradient.
What is the function of a sodium potassium pump?
-Found in cell membranes
- acts like a “ sump pump” to pump Na+ and K+ to opposite sides of the cell membrane against the concentration gradient. This, in turn, establishes an electrical gradient.
What is endocytosis?
Method of taking substances into cells that would be too large to be transported by protein carriers
What is phagocytosis?
” cell eating” where solids are taken inside the cell
What is pinocytosis?
” cell drinking” where fluids and small molecules are taken inside the cell.
What is exocytosis?
method of discharging materials from cells ( this is the opposite of endocytosis.)
Autotroph
” self feeder” These are organisms that can make their own food.
Photoautotrophs
Use sunlight to make their food the process of photosynthesis. ( Ex. Plants, cyanobacteria, and some protists)
Chemoautotrophs
strip electrons from hydrogen atoms to make their “food.”
Heterotroph
” other feeder”
An organism that cannot make its own food. Instead, these organisms must eat or prey upon other organisms or absorb nutrients from organic materials ( such as fungus does). Heterotrophs are consumers.
What is the overall equation for carbohydrate ( glucose) breakdown?
Cellular resperation= series of reactions that break down glucose into carbon dioxide and water
glucose+ Oxygen- Carbon Dioxide + water+ energy
What is an electron transport chain? What does it accomplish for cells?
Shuttling system for electrons. When electrons enter the system, they have high energy going in and low energy when they exit. The difference in energy level is used to produce ATP. Electron transport systems allow for the gradual release of energy during metabolic reactions. If all of the energy were released at one, cells would incinerate themselves because too much heat would be released at one time.
The steps in cellular respiration
1) glycolysis ( followed by preparatory steps), 2) the Krebs cycle ( also known as citric acid cycle) and 3) the electron transport chain.
Glycolysis
” glucose splitting” and is the first step in the breakdown of glucose.
Where does glycolysis occur in the cell
the cytoplasm
What are glycolysis end products?
Produces two 3-carbon pyruvate molecules
Does glycolysis require oxygen?
No ( anaerobic)
What is the net gain of ATP from glycolysis?
produces 2 ATP ( net)
What is the role of NAD+ in glycolysis?
that of an electron or energy carrier
Where does the pyruvate go that is produced in glycolysis?
enter the mitochondrion for further processing.
What is fermentation? Where does it occur and when might it occur?
Process that can occur after glycolysis only when there is a lack of oxygen in the cells.
Takes place in cytoplasm no oxygen is used and generates 2 ATP molecules
hat does the “burning”
sensation in overexerted muscles have to do with fermentation
Lactic Acid fermentations- occurs in muscles of animals in response to a lack of oxygen in the tissue
Oxygen Dept
the amount of oxygen that needs to be “ rapid” to muscles cells in order to convert the lactic acid back to pyruvate.
Alcoholic fermentation
occurs in plants, plant products ( fruit), and fungi ( including yeasts) The pyruvate is converted into ethanol ( alcohol).
Preparatory Steps ( also known as the transition reactions)
-occurs just before the Krebs cycle
- occurs in the mitochondrion
What happens in the preparatory steps?
Each pyruvate molecule is combined with a coenzyme A molecules to form acetyl CoA that will enter the first reaction in the Krebs cycle. One molecule of carbon dioxide is also produced for each of the two pyruvate that get processed.
What is the Krebs cycle ( citric acid cycle)
series of ten reactions that are cyclical ( go in a circle). it requires oxygen and the end products are carbon dioxide and 2 ATPs are produced.
Where does the Krebs cycle occur
the mitochondrion
From where does the CO2 that we exhale originate?
originates as carbohydrate.
Electron transport phosphorylation
the electron transport system, electron transport chain, or oxidative phosphorylation
One glucose molecule yields how many total ATP molecules after it is completely broken down by the
processes of glycolysis, the Krebs cycle, and oxidative phosphorylation?
A total of 30-32 ATP molecules. ( 2 ATP from glycolysis, 2 ATP from citric acid cycle, and 26-28 ATP from electron transport system.
What is the role of oxygen in aerobic respiration?
Water i produced when oxygen ( the final electron acceptor) combines with a pari of electrons and H+ ions.
Where does electron transport phosphorylation occur? does it tkae oxygen? what are the end products and how many total ATPs does it produce?
the mitochondrion, it requires oxygen and produces 26-28 ATP,
How does chemiosmotic ATP synthesis work?
1) H+ ions are pumped to one side of a membrane. This creates a concentration gradient of hydrogen ions. There is a lot of potential energy here
2) As the H+ are allowed to flow back across the membrane through a protein channel, an enzyme is activated that allows the 3rd phosphate to be put back on ADP to make ATP.
Leaves appear green, explain.
they reflect the green wavelength of light
What is the general formula for photosynthesis?
Carbon Dioxide+Water+ Energy= Glucode+Oxygen
What are the different kinds of light reactions?
The light-dependent reactions take place in the thylakoids
The light-independent reactions occur in the liquid stroma. ( function is to reduce or convert CO2 to carbohydrate)
What part of the electromagnetic spectrum is utilized by plants for photosynthesis? What wavelengths
are absorbed best?
visible light, the blue and red wavelengths are absorbed the best
Describe the structure of chloroplast
- bound by double membrane
- contains two portions-
a) liquid stroma
b) membranous grana made of thylakiods
Describe the steps in the light-dependent reactions of photosynthesis?
1) sunlight is absorbed by chlorophyll
2) water is split. one-half of an oxygen molecule ( really one atom of oxygen) released to the atmosphere, two hydrogen ions are released to the thylakoid space, and the electrons from this splitting of water replaces those that were boosted in energy from the chlorophyll in steps one above.
3)electrons to the electron transport system ( cytochrome system) the electrons have high energy going in and low energy coming out. The energy released from these electrons is used to make ATP.
4) Electrons leaving the cytochrome system are picked up by P700.the electrons are again boosted to a energy leevel where another high
acceptor molecule passes them to NADP.
The end product is ATP
Describe what occurs in the light-independent reactions of photosynthesis (Calvin cycle). What
substances are fed into the system? What are the end products?
1) ATP and NADPH that were produced in the light-dependent reactions are used here.
2) CO2 combines with a 5-carbon molecule of RuBP ( ribulose diphosphate). This is the first of a cyclical series of chemical reactions in the conversion of carbon dioxide into sugar.
3) it takes six turns of the Calvin-Benson cycle along with six molecules of CO2 produce one molecule of sugar ( glucose).
