WEEK 3: Cellular metabolism Flashcards
(50 cards)
1
Q
What is metabolic activity
A
- Organic molecules are broken down to obtain energy
-> energy is stored as ATP(used to construct new organic molecules)
2
Q
What is energetics
A
how the body balances heat gains and losses
- study of flow of energy and its change from one form to another
3
Q
What do cells needs(6) to carry our reactions
A
- oxygen
- nutrients (water,vitamins,mineral ions,organic substrates)
4
Q
What is metabolism? and what is constists of (2)
A
sum of all chemical and physical changes that occur in body tissues
-> catabolism (catabolic reactions)
-> anabolism (anabolic reactions)
5
Q
What is catabolism
A
- converts large molecules into smaller ones
- breakdown of organic substrates releases energy used to synthesize ATP
6
Q
What is anabolism
A
- converts small molecules into larger ones
- synthesis of new organic compounds is an “uphill” process that forms new chemical bonds
7
Q
What are the 4 functions of anabolism
A
- perform structural maintenance or repairs
- support growth
- produce secretions
- store nutrient reserves
8
Q
What are the 3 main nutrient reserves
A
- Triglycerides
- Glycogen
- Proteins
9
Q
What are Triglycerides
A
most abundant storage lipids
consist primarily of fatty acids
10
Q
What is Glycogen
A
most abundant storage carbohydrate
- a branched chain of glucose molecules
11
Q
What are proteins
A
- most abundant organic components in body
perform many vital cellular functions
12
Q
Describe the oxidation–reduction reaction (redox reaction)
A
- electrons carry chemical energy
- REDUCTION: reduced atom or molecule gains energy(hydrogen/or electrons)
-> electron recipient is reduced - OXIDATION: oxidized atom or molecule loses energy(hyrogen/or atoms)
->electron donor is oxidised
13
Q
What is the electron transport chain
A
- series of protein complexes in mitochondria
- electrons passed through series of oxidation–reduction reactions
- electrons are ultimately transferred to o2->electrons combine with o2 atoms and hydrogen ions, h2o is formed
14
Q
What are coenzymes and 2 examples
A
- play a key role in the flow of energy within a cell
- act as intermediaries
-> accept electrons from one molecule
-> transfer them to another molecule - eg. NAD, FAD
15
Q
What is the coenzyme FAD
A
- accepts 2 hydrogen atoms (gains 2 electrons)
- forming FADH2
16
Q
What is the coenzymes NAD
A
- oxidized form has a positive charge (NAD+)
- accepts 2 hydrogen atoms (gains 2 electrons)
->releases 1 proton
->forming NADH
17
Q
What is carb catabolism+cell rep
A
- generates ATP and other high-energy compounds
- cellular respiration:
->glucose + o2 -> co2 + o2
->involves glycolysis, citric acid cycle+ electron transport chain - one molecule of glucose provides a net gain of 30–32 molecules of ATP
18
Q
What is glycolysis
A
- breaks glucose in cytosol into smaller molecules that can be used by mitochondria
- does not require oxygen (anaerobic reaction)
- breaks 6-carbon glucose
into two 3-carbon molecules of pyruvic acid (ionized form is called pyruvate) - begins when an enzyme phosphorylates a glucose molecule
->creating glucose-6-phosphate
19
Q
What 5 things does glycolysis require
A
- glucose molecules
- appropriate cytosolic enzymes
- ATP and ADP
- inorganic phosphate groups
- NAD (coenzyme)
20
Q
Explain the 7 steps of glycolysis
A
- As soon as a glucose molecule enters the cytosol, a phosphate group is attached to the molecule = Glucose-6-phosphate
- A second phosphate group is attached = Fructose-1,6-bisphosphate
-> Together, steps 1 and 2
cost the cell 2 ATP molecules. - The 6-carbon chain is split
into two 3-carbon molecules - Another phosphate group is attached to each molecule, and NADH is generated from NAD
- One ATP molecule is formed for each molecule processed=produces 2 ATP molecules.
- The atoms in each molecule are rearranged, releasing a molecule
of water - A second ATP molecule is formed for each molecule processed.=produces 2 ATP molecules
21
Q
What is aerobic metabolism
A
- occurs within mitochondria
- requires oxygen
- energy released from breakdown of pyruvate is used to produce a large amount of ATP
- involves citric acid cycle and electron transport chain
22
Q
What are the 3 mitochndrial membrane
A
- Outer membrane
- Inner membrane
- Intermembrane space
23
Q
What is outer membranes
A
contains large pores
permeable to ions and small organic molecules such as pyruvate
24
Q
What is inner membranes
A
contains carrier protein that moves pyruvate into mitochondrial matrix
25
What is intermediate space
separates outer and inner membranes
26
- H atoms of pyruvate are removed by coenzymes
- C and O atoms are removed and released as CO2 in decarboxylation
- In mitochondrion, pyruvate interacts with NAD and coenzyme A (CoA)=producing 1 CO2, 1 NADH, and 1 acetyl-CoA (acetyl group bound to CoA)
- acetyl group transfers from acetyl-CoA to a 4-carbon oxaloacetate molecule=producing 6-carbon citric acid
-CoA is released to bind another acetyl group
-one citric acid cycle removes 2 carbon atoms
regenerating 4-carbon chain
- 1 citric acid cycle produces one molecule of GTP (guanosine triphosphate)
through substrate-level phosphorylation
27
What is Oxidative phosphorylation
generation of ATP through transfer of electrons from NADH and FADH2 to oxygen
-> by a sequence of electron carriers within mitochondria
- produces 95% percent of ATP used by body
- requires oxygen and electrons
- occurs in ETC
28
ETC for NAD steps
- energy of one electron pair removed from substrate in citric acid cycle by NAD
-> pumps 6 hydrogen ions into intermembrane space
-> reentry into matrix generates 2.5 molecules of ATP
29
ETC for FAD steps
- energy of one electron pair removed from substrate in citric acid cycle by FAD
->pumps 4 hydrogen ions into intermembrane space
-> reentry into matrix generates 1.5 molecules of ATP
30
What is Gluconeogenesis
- synthesis of glucose from noncarbohydrate molecules
31
What is glycogenesis
- formation of glycogen from excess glucose
- requires high-energy compound uridine triphosphate (UTP)
32
What is Glycogenolysis
- breakdown of glycogen to glucose monomers
- occurs quickly
- involves a single enzymatic step
33
What is Lipid catabolism (lipolysis)
- breaks lipids down into pieces that can be converted to pyruvate+channeled directly into citric acid cycle
- hydrolysis splits triglyceride into-> 1 molecule of glycerol and 3 fatty acid molecules
- enzymes in cytosol convert glycerol to pyruvate
-> pyruvate is converted to acetyl-CoA and enters citric acid cycle
34
What is Beta-oxidation
- sequence of reactions inside mitochondria
- breaks fatty acid molecules into 2-carbon fragments
- FAD and NAD+ are reduced
- generates molecules of acetyl-CoA, NADH, and FADH2
- leaves a shorter carbon chain bound to CoA
35
What is lipid synthesis(lipogenesis)
- can use almost any organic substrate
- because lipids, amino acids, and carbohydrates can be converted to acetyl-CoA
36
What is glycerol
- synthesized from dihydroxyacetone phosphate
- an intermediate product of glycolysis and gluconeogenesis
37
What are essential fatty acids
- cannot be synthesized in the body
- must be consumed
- example: linoleic acid and linolenic acid
38
The functions of lipid storage
- provides important energy reserves
- can slowly provide large amounts of ATP
- difficult for water-soluble enzymes to reach
39
Wha is lipid transport and distribution and why is it important
- most lipids are not soluble in water
special transport mechanisms carry lipids from one region to another
->most lipids circulate through bloodstream as lipoproteins
its important bc:
- cells require lipids to maintain plasma membranes
- steroid hormones must reach target cells in many different tissues
40
What are free fatty acids (FFAs)
- can diffuse easily across plasma membranes
- in blood, they are generally bound to albumin (most abundant plasma protein)
- important energy source during periods of starvation
- when glucose supplies are limited
- cells in liver, cardiac muscle, skeletal muscle, etc=can metabolize free fatty acids
41
What are the sources of FFAs in blood
- those not used in synthesis of triglycerides that diffuse from intestinal epithelium
- those that diffuse out of lipid reserves when triglycerides are broken down
42
What are lipo proteins?
- lipid–protein complexes
- contain large insoluble glycerides and cholesterol
43
What are the 4 groups of lipo proteins
- chylomicrons
- very low-density lipoproteins (VLDLs)
- low-density lipoproteins (LDLs) - “bad cholesterol”
- high-density lipoproteins (HDLs) - “good cholesterol”
44
What are chylomicrons
- largest lipoproteins
- produced by intestinal epithelial cells from fats in food
- carry absorbed lipids into lymph and then into bloodstream
45
Explain protein metabolism
- body synthesizes 100,000 to 140,000 different proteins
->each with different structures and functions
->all proteins are built from same 20 amino acids
- proteins function as enzymes, hormones, structural elements, and neurotransmitters
- very little protein is used as an energy source
46
What is Amino acid catabolism and processes it involves
- for proteins to be used as energy
-> must be converted into substances that can enter citric acid cycle
- This conversion involves
->transamination
->deamination
->urea cycle
- removal of amino group requires a coenzyme derivative of vitamin B6
46
What is Transamination
- attaches amino group of amino acid to keto acid
- converts keto acid into amino acid
->leaves mitochondrion and enters cytosol
->available for protein synthesis
47
What is Deamination
- prepares amino acid for breakdown in citric acid cycle
- removes amino group and hydrogen atom
->generating a toxic ammonium ion
- generates ammonium ions primarily in liver cells
- liver cells have enzymes that remove toxic ammonium ions by synthesizing urea
->through the urea cycle
->urea is a fairly harmless water-soluble compound excreted in urine
48
What are 3 factors that make protein catabolism impractical
- proteins are more difficult to break apart than complex carbohydrates or lipids
- one by-product (ammonium ions) is toxic to cells
- proteins form the most important structural and functional components of cells
49
What is protein synthesis
- body synthesizes half of the amino acids needed to build proteins
- Ten essential amino acids
eight are not synthesized at all
two are insufficiently synthesized
- Nonessential amino acids
amino acids made by the body on demand
- requires amination (addition of an amino group)
