PCAT Biology Flashcards
Metabolism can be divided into Two reactions. They are?
- Catabolic
2. Anabolic
What are catabolic reactions?
They BREAK DOWN large chemicals and RELEASE energy
What are Anabolic reactions?
They BUILD UP large chemicals and REQUIRE energy
What is Homeostasis?
The body’s metabolism functions to maintain its internal environment in a changing external environment.
What do Enzymes Do?
- They affect the reaction rate by decreasing the activation energy.
- They can speed up or slow down chemical reactions
What are Conjugated Proteins?
They are complex proteins consisting of amino acids COMBINED WITH OTHER SUBSTANCES. ( the other substances are known as prosthetic groups and they can be covalently bonded or positioned by other forces to the protein. )
What effects enzyme action and the reaction rate?
pH
Temperature
Concentration of enzyme and substrate
Lock and Key Theory
Spatial structure of an enzyme’s active site is exactly complementary to the spatial structure of its substrate. (triangle block fits into triangle space)
Induced fit Theory
When the appropriate substrate comes in contact with the active site, the conformation of the active site changes to fit the substrate
True or False: Most enzyme reactions are reversible
True
Maximal activity of many human enzymes occur at what pH?
7.2
What is pepsin and what pH does it operate in?
Enzyme found in stomach and works best in highly acidic conditions (pH = 2)
Where do pancreatic enzymes Operate and what pH do they work best in?
They operate mainly on the small intestine with an optimal pH of 8.5
Competitive Inhibition
If a similar molecule is present in a concentration comparable to the concentration of the substrate, it will COMPETE WITH THE SUBSTRATE for binding sites on the enzyme and INTERFERE with enzyme activity.
Solution to competitive inhibition?
Raise the concentration of the substrate
Noncompetitive Inhibition
a substance that forms strong covalent bonds with an enzyme and consequently may not be displaced by the addition of excess substrate. therefore, IT IS IRREVERSIBLE.
Allosteric inhibition
- Form of Noncompetitive inhibition
2. A non competitive inhibitor that inhibits at a site other than the active site ( rear end)
What does hydrolysis do?
- form of enzyme activity
2. digest large molecules into smaller components
What does Lactase do?
- form of enzyme activity
2. Hydrolyzes lactose to glucose and galactose
What does Protease do?
- form of enzyme activity
2. Degrade proteins to amino acids
What does Lipases do?
- Form of enzyme activity
2. breaks down lipids –> Fatty acids + Glycerol
What are synthesis reactions catalyzed by?
Which direction do they go in?
What are they important for?
- catalayzed by same enzymes as hydrolysis rxns except in reverse direction.
- required for growth, repair, regulation, protection, and production of food reserves such as glycogen and fat by the cell.
What are Cofactors?
How can they be obtained?
- Metal Cations ( Zn2+ or Fe2+) or small organic coenzymes that bind that enzyme by strong covalent bonds. (prosthetic groups)
- Cant be synthesized by body and obtained from diet.
What are prokaryotes?
“before nucleus” cells that lack nucleus(bacteria)
What are Eukaryotes?
Cells that have nucleus (us)
What is a Cell Membrane/plasma membrane?
- Regulates passage of materials into and out of the cell.
2. Consists of Phospholipid Bilayer with proteins embedded throughout.
Which parts are Hydrophobic and hydrophilic on the phospholipid bilayer?
The Head ( Hydrophilic) - phosphorous The Tail ( Hydrophobic) - C's and H's
Can Large charged ions and charged molecules cross the cell membrane ?
They can, only with the assistance of CARRIER proteins
What does the nucleus do?
What does it contain?
- Controls activities of the cell, including cell division
2. it contains DNA which is complexed with histones.
What are Histones?
- Proteins that are closely associated with DNA molecules,
- Responsible for forming chromosomes.
- Responsible for structure of chromatin and regulation of gene expression.
Whats special about the nucleolus?
Its a dense structure IN THE NUCLEUS where RIBOSOMAL RNA (rRNA) SYNTHESIS OCCURS
Whats special about ribosomes?
Two locations of ribosomes?
- they are synthesized by nucleolus
- site of protein production
Free ribosomes found in cytoplasm
Bound ribosomes line the outer membrane of Endoplasmic Reticulum (ER)
Purpose of endoplasmic reticulum (ER) ?
two types?
involved in TRANSPORT of materials throughout the cell
(materials that are going to be secreted by the cell)
Rough ER: has ribosomes attached to them
Smooth ER: has no ribosomes attached
Rough ER vs Smooth ER
Rough ER: where molecules and proteins are made
Smooth ER: Metabolizes certain compounds and synthesis of lipids and steroids. also secretes proteins into cytoplasmic vesicles that are transported to the golgi apparatus
what does Golgi Apparatus do?
- package and processes proteins, lipids etc. that are synthesized by the cell.
- Modifies and sorts them and repackages them into vesicles
Why is the mitochondria important?
- they are sites of aerobic respiration within the cell
2. provides energy for cell
What does the cytoplasm consist of?
what is it responsible for?
- consists of all of the contents outside of the nucleus and enclosed within the cell membrane of a cell.
- Fluid that fills up the cell
- Most of cells metabolic activity occurs here.
- helps to move materials around the cell and also dissolves cellular waste.
Cyclosis
It is the streaming movement within the cell that helps transports molecules within the cytoplasm
what is Exocytosis?
- the vacuole membrane fuses with the cell membrane
- the contents of the cell vacuole are then released outside the cell surface
- DUMPING STUFF OUT OF CELL
what are Vacuoles/Vesicles?
What do they do?
Membrane-bound sacs involved in transport and STORAGE of materials that are ingested, secreted, processed , or digested by the cell
- Storage bubbles found in cells
- store nutrients that cells need to survive
- store waste products to protect cell from contamination
What are centrioles?
what are they made up of?
- they are involved in spindle organization during cell division.
- composed of microtubules
- direct the separation of chromosomes during cell division
True or False: plant cells contain centrioles
False, only animal cells
what do Lysosomes contain?
what do they do?
Importance of lysosomal membrane?
- contains hydrolytic enzymes involved in digestion within the cell.
- Breaks down material ingested by the cell. 3. The products of the lysosomal digestion are released into the cytoplasm where they can be used by the cell.
- hydrolytic enzymes would digest cellular components without the lysosomal membrane (killing the cell)
What is autolysis?
- An injured or dying cell commits suicide by rupturing the lysosome membrane and releasing its hydrolytic enzymes.
- the DESTRUCTION of cells or tissues by their OWN ENZYMES
What is the significance of cytoskeleton?
- it supports the cell
- Maintains cell shape
- Functions as cell motility
What is the cytoskeleton composed of?
- Microtubules
- Microfilaments
- Intermediate filaments