Chapter 7- The Basis of Life Flashcards
Metabolism
The sum of all chemical reactions that occur in the body.
What to reactions can metabolism be broken down into? Describe Both.
Catabolic- Break down of large chemicals to release energy
Anabolic- Build up large chemicals and require energy
Ingestion
The acquisition of food and other raw materials
Digestion
The process of converting food into a usable soluble form so that it can pass through membranes in the digestive tract and enter the body.
Absorption
The passage of nutrient molecules through the lining of the digestive tract into the body proper
How do absorbed molecules pass through cells lining the digestive tract?
By diffusion or active transport
Transport (2 clauses)
- The circulation of essential compound required to nourish the tissues
- The removal of waste products from the tissues
Assimilation
The building up of new tissues from digested food materials
Respiration
The consumption of oxygen by the body.
Cells use oxygen to….
Covert glucose into ATP, which is a ready source of energy for cellular activities
Excretion
The removal of waste products (such a CO2, water, and urea) produced during metabolic processes like respiration and assimilation.
Synthesis
The creation of complex molecules from simple one, also known as anabolism
Regulation
The control of physiological activities.
Homeostasis
The maintenence of the body’s internal encironment in a changing external environment by the body’s metabolism function.
Includes hormones and the nervous system.
Irritability
The ability to respond to a stimulus and is part of regulation.
Growth
An increase in size caused by a synthesis of new materials
Photosynthesis
The process by which plants convert CO2 and H2O into carbohydrates. Sunlight is harnessed by chlorophyll to drive this reaction.
Reproduction
The generation of additional individuals of a species.
All living things are composed to the elements
Carbon Hydrogen Oxygen Nitrogen Sulfur Phosphorus
and TRACES of Magnesium Iodine Iron Calcium Other minerals
Protoplasm
The substance of life
Atom
Unit of an element
Molecule
Unit of a compound
Compounds. Give examples.
Formed by the chemical bonds of atoms
Water, CO2, Carbon dioxide
The chemical compounds in living matter can be divided into?
Organic and Inorganic compounds
Inorganic Compounds
Compounds that do not contain the element carbon, including salts and HCL
Organic Compounds
Made by living systems and contain carbon. They include carbohydrates, lipids proteins, and nucleic acids
Carbohydrates
Composed of carbon, hydrogen, and oxygen in a 1:2:1 ratio
Used as storage formed of energy or as structural molecules
What stores energy in animals vs plants?
Animals: Glucose and glycogen
Plants: Starch
Monosaccharides
Singe sugar subunits: Such as glucose and fructose
Describe the formula and structure of glucose
C6H12O6
Has a hexagonal structure with a six-carbon ring and H and OH bonded to each carbon
Disaccharide
Composed of two monosaccharide subunits
examples: Maltose and sucrose
Dehydration synthesis
Joins together single subunits by loss of a water molecule
Polusaccharide
Polymers or chains of repeating monosaccharide subunits.
Example: Glycogen and starch
Cellulose
A polysaccharide that serves a structural role in plants. Insoluble in water.
How are polysaccharides formed? Broken?
Formed by removing water (dehydration)
Broken down by adding water (hydrolysis)
Lipids
Fats and Oils
Composed of C,H, and O but H:O ratio if much greater than 2:1.
Consists of 3 fatty acids molecules bonded to a single glycerol backbone
Properities of Fatty Acids
Have long carbon chains that give the their hydrophocin (fatty) character and carboxylic acid groups that make them acidic
What needs to happen in order to form one fat molecule?
Three dehydration reactions
True/ False: Lipids form polymers
False.
Draw how glycerol+fatty acids synthesize a lipid
Draw on paper.
Lipids are the chief means of what? Why?
Food storage in animals.Because they release more energy per gram weight than any other class of biological compounds.
What roles do lipids play other than storage?
Provide insulation and protection against injury because they are a major component of adipose (fatty) tissue
List 5 lipid derivatives:
- Phospholipids
- Waxes
- Steroids
- Carotenoids
- Porphyrins
Phospholipids
Contain glycerol, two fatty acids, a phosphate group, and nitrogen-containing alcohol such as lecithin and cephalin
Waxes
Type of lipid
Esters of fatty acids and monohydroxylic alcohols. They are found as protective coatings on skin, fur, leaves of higher plants, and on the exoskeleton of many insects
Steroids
Have 3 fused cyclohexane rings and one fused cyclopentane ring.
Include: Cholesterol
Sex hormones: testosterone and estrogen
Corticosteroids
Cartenoids
Fatty, acid-like carbon chains containing conjugated double bonds and carrying six-membered carbon rings at each each
Pigments that produce red, yellow, orange, and brown colors
Examples: carotenes, and xanthophylls
Porphyrins
Also called tetrapyrroles
Contain 4 joined pyrrole rings. They are often complexed with metals
Example: heme- complexes with FE in hemoglobin.
Chlorophyll is complexed with Mg
Proteins are composed primarily of elements
C, H, O, and N but may also contain phosphorus and sulfur
Proteins are polymers of amino acids
Amino acids are joined by:
Peptide bonds through dehydration reactions
Chains of such bonds form a polypeptide
Primary structure
Sequence of amino acids
Secondary Structure
Based on hydrogen bonding between adjacent amino acids and results in beta-pleated sheets or alpha-helices
Tertiary Structure
3-D structure that is based on R-group interactions between adjacent amino acids.
Hydrophobic amino acids are crowded in the center with the hydrophilic amino acids at the outer edge.
What is a result of a tertiary structure?
Globular or fibrous proteins
Quaternary Structure
The interaction and joined of two or more independent polypeptide chain
Proteins can be classified on..
the basis of structure
Simple proteins
Composed o entirely amino acids
Albumins and globulins
Primarily globular in nature. Functional proteins that act as carriers or enzymes
Scleroproteins
Fibrous in nature and act as structural proteins. Example: Collagen
Conjugated proteins
These contain a simple protein portion plus at least one nonprotein fraction
Lipoproteins
Proteins bound to lipid
Mucoproteins
Proteins bound to carbohydrate
Chromoproteins
Proteins bounds to pigmented molecules
Metaloproteins
Proteins complexed around a metal ion
Nucleoproteins
Proteins containing histone or protamine (nuclear protein) bounds to nucleic acids
Hormones
Proteins that function as chemical messengers secreted into the circulation.
Example: Insulin and ACTH
Enzymes
Biological organic catalysts that act by increasing the rate of chemical reactions.
This is done by decreasing the activation energy
Example: Amylase, lipase, ATPase
Structural proteins
Contribute to the physical support of a cell/tissue.
May be extracellular
example: Collagen in cartilage, bone, and tendons
May be intracellular
example: Proteins in cell membranes
Transport proteins
Carriers of important materials
Example: Hemoglobin- carried oxygen in the circulation
Cytochromes- carry electrons during cellular respiration
Antibodies
Proteins that bind to foreign particles (antigens), including disease-causing organisms that have entered the body.
What is a catalyst?
Any substance that affects the rate of a chemical reaction without itself being changed
Why are enzymes crucial to living things?
All living things must maintain a continuous controlled chemical activity. Enzymes regulate metabolism by speeding up or slowing down certain chemical reaction
Coenzyme
Enzyme conjugated with a non-protein. Both parts much be present for the enzyme to function
Selectivity of an enzyme
Enzymes are very selective, they may catalyze only one reaction or one specific class of closely related reactions
Substrate
The molecule upon which an enzyme acts
Active site
The area in an enzyme where the substrate binds
3 facts about enzymes
- Do not alter eq. constant
- Not consumed by the reaction. They will appear both in the reactants and products
- Are pH and temp sensitive, with optimal activity at certain pH and temps.
Lock and Key theory
Discounted theory
Substrate and enzyme fit together like lock and key.
Receptors are large proteins that contain a recognition site (lock) that is directly linked to transduction systems.
When a substrate (key) binds to it, a sequence of events in started.
Induced fit theory
Describes the active site as having flexibility of shape. When the appropriate substrate comes in contact with the active site, the conformation of the active site changes to fit the substrate.
Most enzyme reactions are reversible. Explain this
The product synthesized by an enzyme can be decomposed by the same enzyme.
As the temp increases, the rate of enzyme activity…
increases
What happens to an enzyme beyond optimal temperature?
Heat alters the shape of the active site of the enzyme molecule and deactivates it, leading to a drop in rate.
What pH does maximal activity occur in humans?
usually pH 7.2.
exceptions:
pepsin: which words best in pH 2 (stomach acidity).
Pancreatic enzymes: work optimally in alkaline conditions of the small intestine (8.5).
How do the concentrations of substrate and enzyme affect the reaction rate?
- When the concentrations of both enzyme and substrate are low, many of the active sites on the enzyme are not occupied
- Increase the substrate concentration will increase reaction rate until all of the active sites are occupied.
- After this point, further increase in substrate concentration will not increase the reaction rate.
Competitive inhibition
- Even though the active site is specific for a certain substrate, it is possible for molecules that are similar to the substrate to bind to the active site.
- This interferes with enzyme activity.
- Called competitive inhibition because the enzyme is inhibited by the inactive substrate.
Noncompetitive inhibitor
- A substance that forms a strong covalent bonds with an enzyme and may not be displaced by addition of substrate
- Irreversible!
- May be bonded near or far from the active site (allosteric)
- The interaction of an inhibitor at an allosteric site changes the structure of the enzyme so that the active site is also changed.
Hydrolysis
Reaction that function to digest large molecules into smaller components.
Lactase
Hydrolyzes lactose to the monosaccharides glucose and galactose
Proteases
Degrade proteins to amino acids
Lipase
Break down lipids to fatty acids and glycerol
Synthesis reaction can be catalyzed by the
same enzymes as hydrolysis reactions but the directions of the reactions are reversed
Synthesis is required for:
Growth, repair, regulation, protection, and production of food reserves such as fat and glycogen.
Cofactors
- Many enzymes require the incorporation of a nonprotein molecule to become active.
- Can be metal cations
- or small organic groups called coenzymes
- coenzymes cannot be synthesized by the body and are obtained from the diet as vitamin derivatives.
Prosthetic Groups
Cofactors that bind to the enzyme by strong covalent bonds
5 points of the Cell Theory
1- All living things are composed of cells
2- The cell is the basic functional unit of life
3- The chemical reactions of life take place inside the cell
4- Cells arise only from pre-existing cells
5- Cell carry genetic information in the form of DNA. This genetic material is passed from parent cell to daughter cell.
5 kingdoms of living things
- Monerans
- Protists
- Fungi
- Plants
- Animals
Basic role of the cell membrane:
Encloses the cell and exhibits selective permeability; regulates the passage of materials in and out of the cell.
What is the fluid mosiac model?
The cell membrane consists of a phospholipid bilayer with proteins embedded throughout. The lipid and many of the proteins can move freely within the membrane.
How does the phospholipid bilayer form and how is it arranged?
Forms spontaneously. Phospholipid molecules are arranged in this way:
- The long, non polar and hydrophobic fatty chains of carbon and hydrogen face each other
- The phosphorous containing, polar and hydrophilic heads face outwards
Head: faces water inside and outside the cell
Tail: Face each other– water free region
What is a plasma membrane permeable and impermeable to?
- Small, non polar hydrophobic molecules such as oxygen
- Small polar molecules such as water
- Small charged materials pass through protein channels
- Charged ions and large charged materials can only cross with carrier proteins
Function of a nucleus
-Controls the activities of the cell, including cell division.
What is the nucleus surrounded by?
Nuclear membrane
What does the nucleus contain?
1- The DNA- which if complexed with structural proteins called histones to form chromosomes.
2- Nucleolus- Dense structure in the nucleus where ribosomal RNA (rRNA) synthesis occurs.
Function of a ribosome
The sites of protein production
Where are ribosomes produced?
Nucleolus
What are the two types of ribosomes and where are they found?
Free ribosomes: found in the cytoplasm
Bound ribosomes: line the outer membrane of the endoplasmic reticulum (rough)
Endoplasmic reticulum
A network of membrane-enclosed spaces involved in the transport of materials throughout the cell- especially materials destined to be secreted by the cell.
Golgi apparatus
Receives vesicles and their contents from the smooth ER, modifies them, repackages them into vesicles, and distributes them to the cell surface by exocytosis.
Mitochondria
Composed of an outer and inn er phospholipid bilayer. Sites of aerobic respiration within the cell and hence the suppliers of energy.
Cytoplasm
Where most of the cell’s metabolic activity occurs.
Cyclosis
Streaming movement within the cell- how transport within the cytoplasm occurs
Vacuoles/ Vesicles
Membrane-bound sacs involved in the transport and storage of materials that are ingested, secreted, processed or digested by the cell.
Difference between vacuoles and vesicles
Pretty much have the same function
Vacuoles are larger than vesicles and are likely to be found in plant cells than in animal cells.
Centrioles
Involved in spindle organization during cell division
True/ False: Centrioles are bound by membranes:
False
True/ False: Plant cells do not have centrioles:
True
Centrosome
A region in animal cells where a pair of centrioles are oriented at right angles to each other
Lysosomes
Membrane-bound vesicles that contain hydrolytic enzyme involved in intracellular digestion. Breakdown material ingested by the cell.
Autolysis
An injured or dying tissue may commit suicide by rupturing the lysosome membrane and releasing its hydrolytic enzymes
Cytoskeleton
Supports the cell, maintains its shape, and function in cell motility. Is located in the cell cytoplasm.
What is a cytoskeleton composed of?
Microtubules, microfilaments, and intermediate filaments
What are microtubules?
Hollow rods made up of polymerized tubulin that radiate throughout the cell and provide it with support. Provide a framework for organelle movement within the cell.
True or False: centrioles are composed of microtubules
True
Cilia and Flagella
Specialized arrangements of microtubules that extend from certain cells and are involved in cell motility and cytoplasmic movement
Microfilaments
Solid rods of actin, important in cell movement as well as support
An example of when microfilaments move materials across the plasma membrane
The contraction phase of cell division and in amoeboid movement
5 ways that plant cells differ from animal cells
- No centrosome
- Presence of cell wall composed of cellulose
- Chloroplasts in many cells of green plants are sites of synthesis of organic compounds (photosynthesis)
- No lysosomes
- Many vacuoles/ mature plant cells usually contain one large vacuole
Simple and facilitated diffusion are examples of?
passive transport
What is active transport?
Movement of molecules against the concentration gradient with the help of transport proteins.
Simple diffusion
Net movement of dissolved particles down their concentration gradients– from a region of higher concentration to a region of lower concentration. No external energy required.
Osmosis
Simple diffusion of water from a region of low solute concentration to high solute concentration
When the medium is hypertonic to the cell:
The cytoplasm of a cell has a lower solute concentration than the extracellular medium.
Water will flow out of the cell and call the cell to shrivel (plasmolysis).
When the medium is hypotonic to the cell:
The extracellular environment is less concentrated than the cytoplasm of the cell, which causes the cell to swell and burst (lyse)
Facilitated diffusion
Passive transport– net movement of dissolved particles down their concentration gradient through special channels or carrier proteins in the cell membrane. No external energy required.
Active transport
Net movement of dissolved particles against their concentration gradient with the help of transport proteins. Required energy
Carrier molecules
Help aid in the regulation of the cell’s internal content of ions and large molecules.
4 types of carrier molecules
- Energy independent carriers
- Symporters
- Antiporters
- Pumps
Energy independent carriers
Facilitate the movement of compounds along a concentration gradient
Symporters
Move two or more ions or molecules
Antiporters
Exchange one or more ions (or molecules) for another ion or molecule
Pumps
Energy-dependent carriers (require ATP) for example: Na+-K+ pump
Endocytosis
Pino
Phago
A process in which the cell membrane invaginates, forming a vesicle that contains extracellular medium
Pinocytosis
Ingestion of fluids or small particles
Phagocytosis
Engulfing of large particles. Particles may bind to receptors on the cell membrane before engulfed.
Exocytosis
A vesicle within the cell fuses with the cell membrane and releases its contents to the outside
Fusion of the vesicle within the cell can play an important role in:
cell growth and intercellular signalling
True or False: in both endocytosis and exocytosis, the material never actually crosses through the cell membrane:
TRUE
Circulation
Transportation of material within cells and throughout the body of a multicellular organism
Brownian movement
Type of intracellular circulation– kinetic energy spreads small suspended particles throughout the cytoplasm of the cell
Cyclosis or streaming
The circular motion of cytoplasm around the cell transports molecules
Endoplasmic reticulum
This provides channels throughout the cytoplasm and provides a direct continuous passageway from the plasma membrane to the nuclear membrane.
Extracellular circluation
Movement of materials on a larger scale though the body of an organism. Examples: diffusion and the circulatory system
Diffusion
When cells are in direct or close contact with the external env., diffusion serves as a sufficient means of transport for food and oxygen from the environment to the cells
Circulatory systems are important in
complex animals whose cells are too far from the external environment to transport materials by diffusion
What is the circulatory system?
vessels to transport fluid and a pump to drive circulation
