Unit 4 Flashcards
(129 cards)
1
Q
What do cells need for energy?
A
Glucose
2
Q
Can cells store glucose?
A
No, they rely on the blood to provide them with the glucose they need
3
Q
Where does glucose come from?
A
The intestines, from food that was just digested and absorbed), or from the liver, glycogen breakdown or gluconeogenesis
4
Q
What is the storage form of glucose?
A
Glycogen
5
Q
Where is glycogen found?
A
In the liver and muscles
6
Q
What makes up glycogen?
A
Many glucose molecules that are branched which allows for rapid hydrolysis when glucose is needed in the blood
7
Q
What is gluconeogenesis?
A
The making of glucose from a non-carbohydrate source. e.g. the conversion of an amino acid to glucose
8
Q
How does the body use glucose to function optimally?
A
The body must maintain blood glucose levels within limits that allow cells to nourish themselves.
9
Q
What happens if a person’s blood glucose level drops below normal limits?
A
They may get dizzy and weak
10
Q
What happens if a person’s blood glucose level rises above normal?
A
They may become fatigued
11
Q
What is normal fasting blood glucose?
A
70-110 mg/dl
12
Q
What peptide hormones regulate blood glucose?
A
Insulin and glucagon
13
Q
What happens after a meal, when blood glucose rises?
A
Specialized cells of the pancreas called beta cells secrete insulin into the blood
14
Q
What does Insulin do?
A
It makes contact with receptors on cells and the cells respond by allowing glucose in.
15
Q
What cells secrete insulin?
A
Beta cells of the pancreas
16
Q
What cells take in excess glucose and store it?
A
Liver and muscle cells take in excess and convert it to glycogen for storage
17
Q
How many grams can the liver store of glycogen?
A
The liver can store 70 g (or 280 Calories) of glycogen
18
Q
How many grams can the muscle store of glycogen?
A
The muscle can store about 120 g (or 480 Calories) of glycogen
19
Q
What does glycogen in the muscle provide energy for?
A
Continually provides energy to the muscles
20
Q
When do elevated blood glucose levels return to normal?
A
After the excess has been stored as glycogen or fat
21
Q
How does the body make fat?
A
The liver breaks glucose into smaller molecules and puts them together to make fat
22
Q
Where does the fat go after being created in the liver?
A
The fat then travels to the adipose tissues of the body for storage. Fat cells can store seemingly unlimited quantities of fat.
23
Q
What does the body do when blood glucose levels falls (as occurs in between meals)?
A
alpha cells of the pancreas secrete glucagon into the blood
24
Q
What does glucagon do?
A
It raises blood glucose by signaling the liver to break down its glycogen stores and release glucose into the blood
25
What is the main function of lipoproteins?
Transporting vehicles that allow fats to be transported through the watery blood stream
26
What are the main types of lipoproteins?
1. Chylomicrons
2. Very Low Density Lipoproteins
3. Low Density Lipoproteins
4. High Density Lipoproteins
27
What lipoprotein is the largest and least dense of the four lipoproteins?
Chylomicrons
28
What do chylomicrons transport?
Transport diet-derived lipids (mostly triglycerides) from the small intestine to the rest of the body
29
Where are chylomicrons made?
In the small intestine
30
What happens as chylomicrons travel through the body?
Cells all over the body remove triglycerides from the chylomicrons as they pass by and the chylomicron gets smaller and smaller.
31
How long does it take for most of the triglycerides to be depleted from a chylomicron?
14 hours
32
What is left after 14 hours in a chylomicron?
Remnants of protein, cholesterol, and phospholipids
33
How are chylomicrons removed from the blood?
Special protein receptors on the membranes of the liver cells recognize and remove chylomicron remnants from the blood. The liver dismantles the remnants and uses or recycles the pieces
34
What is the most active site of fat synthesis?
The liver
35
What happens to excess things we eat?
It is stored as fat
36
What does the liver do?
In charge of storing excess food as fat, making cholesterol, fatty acids, lecithin, etc.
37
Where are Very Low Density Lipoproteins made?
In the liver.
lipids made in the liver and those collected from chylomicron remnants are packaged with proteins as VLDLs and shipped to other parts of the body via the blood.
38
What do VLDL's drop off to other cells?
Triglycerides
39
What do VLDL's become?
Low-density lipoproteins containing remaining cholesterol rich lipoproteins
40
What are LDL's used for?
They make their contents (of cholesterol) available to cells such as heart, fat stores, mammary glands, and muscles. The cells use the contents to make membranes, hormones, or for storage.
41
What do fat cells release in the body?
May release glycerol, cholesterol, fatty acids, and phospholipids into the blood vessels
42
What are HDL's used for?
The liver makes HDLs to carry cholesterol from the blood back to the liver for recycling or disposal. Some HDLs donate cholesterol to other lipoproteins.
43
What lipoprotein is the most dense?
HDL's because of the high level of protein
44
Why are HDLs "good"?
They clean up the cholesterol in the blood and from dying cells and other sources.
45
Are HDL and LDL cholesterol?
No, they are lipoproteins
46
What is at a high percent in LDL?
LDL has a high percent of cholesterol and delivers fat to cells.
47
What is at a high percent in HDL?
HDL is high in protein and picks up fat from the arteries.
48
Why do we eat protein?
To obtain the amino acids so that we can build proteins in the body
49
What is protein synthesis?
Making proteins that are needed
50
What is proteins degradation?
The breakdown of proteins
51
What is protein turnover?
The cycle of making and breaking down proteins
52
What is an Amino Acid pool used for?
Cells contain an Amino Acid pool that is made of all the amino acids available for use in the body
53
What does the cell make from the AA pool?
Proteins, Neurotransmitters, Melanin, Niacin, Creatine phosphate, Histamine, DNA and RNA
54
Can the body substitute amino acids from the pool?
NO
55
What if there aren't enough amino acids?
Transamination occurs
56
What is transamination?
The process by which an amino group from one amino acid is transferred to a carbon compound to fem a new amino acid
57
Does transamination work with essential amino acids?
It only occurs when it is a non-essential amino acid that is needed. If it is an essential amino acid that is needed, the body is going to have to break down an existing functioning protein to obtain it.
58
What happens if the body cannot obtain the needed amino acids?
Protein synthesis will halt (certain needed proteins will not be made)
59
How is the synthesis of body proteins determined?
Through a process called gene expression
60
What is gene expression?
The process by which cells use genes to make proteins
61
What is a gene?
A segment of DNA that serves as instructions for the synthesis or expression of a particular protein
62
What are the two steps of protein synthesis?
Transcription and translation
63
What is transcription?
A stretch of DNA (in the nucleus) is used as a template to make a strand of RNA known as messenger RNA (mRNA)
64
What happens after transcription?
The mRNA strand then crosses the nuclear membrane into the cytoplasm of the cell, taking the coding instructions with it.
65
What is Translation?
The mRNA attaches itself to one of the ribosomes (protein making machine). mRNA specifies the sequence in which the amino acids line up for synthesis of a protein
66
What does transfer RNA (tRNA) do?
It collects amino acids from the cell fluid and brings them to the mRNA
67
What happens once the protein is made?
tRNA is release to be recycled and used again
68
What is photosynthesis?
The process by which plants use the sun's energy to make carbohydrates from carbon dioxide and water
69
What happens during photosynthesis?
Plants make simple sugars from carbon dioxide and capture the sun's light energy in the chemical bonds of those sugars
70
Where does all the energy that sustains human life come from?
The sun
71
What is metabolism?
The sum total of all the chemical reactions that go on in living cells
72
At what level does metabolic work occur?
The cellular level.
73
What is a metabolic pathway?
A group of biochemical reactions that occur in a progression from beginning to end.
74
What are anabolic reactions?
Reactions in which small molecules are put together to build larger ones. Require energy
75
What are catabolic reactions?
Reactions inw which large molecules are broken down to smaller ones. Release energy
76
What reactions require energy?
Anabolic reactions
77
What reactions release energy?
Catabolic reactions
78
What do metabolic reactions almost always need?
Enzymes to facilitate their actions.
79
What are coenzymes?
Helpers of enzymes. Some coenzymes have B vitamins as part of their structure.
80
Are coenzymes proteins?
NO
81
Can an enzyme function without its coenzyme?
No
82
What is the first pathway that glucose takes to yield energy?
Glycolysis
83
What is glycolysis?
The metabolic breakdown of one glucose molecule into two pyruvate molecules
84
What type of reaction is glycolysis?
An anaerobic process not requiring oxygen.
85
Does glycolysis require oxygen?
NO
86
Where does glycolysis occur?
In the cytosol
87
What does glycolysis require and release
Requires ATP and releases energy
88
What is the pathway if the cell needs energy (ATP)?
Pyruvate to acetyl CoA. (catabolic, aerobic)
89
What is the pathway if the cell does not need energy?
Pyruvate to glucose (glycolysis backwards) AKA gluconeogenesis
90
What is gluconeogenesis?
The making of glucose from a non-carbohydrate source.
91
Does gluconeogenesis require energy?
Yes it is anabolic
92
What happens if the cell needs energy and oxygen is available?
Pyruvate to Acetyl CoA
93
What happens if the cell needs energy and oxygen is not available?
Cori cycle (pyruvate to lactate or lactic acid)
94
What happens from pyruvate to acetyl CoA?
The 2 pyruvate molecules are broken down to 2 acetyl CoA molecules. Acetyl CoA is a 2 carbon molecule with a coenzyme A attached to it.
95
What happens to the extra carbon that was removed from pyruvate?
It become CO2 and is released into the blood, circulated to the lungs, and breathed out.
96
Can Acetyl CoA be used again?
NO, it cannot be used to make pyruvate again and therefore, cannot be used to make glucose
97
Where does the conversion of pyruvate to acetyl CoA occur?
In the mitochondria of the cell
98
What can acetyl CoA do once it is produced?
1. Be metabolized to ATP
| 2. Be redirected into fatty acid synths, this is how fat can be made from sugar.
99
Can acetyl CoA be transferee back across the mitochondrial membrane?
Not without being converted to citrate
100
When does the Cori Cycle occur?
When less oxygen is available pyruvate is converted to lactic acid. It occurs in cells with little or no mitochondria, like RBC's and the lens and cornea of the eye.
101
What accumulates in the muscles during high intensity exercise using the Cori Cycle?
Lactic Acid, which causes the pH of the blood to drop and become more acidic therefore you feel burning pain and fatigue
102
What does the liver convert lactic acid to?
Glucose
103
What do muscles do with lactic acid?
Muscle cells cannot convert lactic acid to glucose because they lack the enzymes to do so.
104
What happens to the acetyl CoA if the cell needs energy?
The Acetyl CoA enters the citric acid (krebs) cycle. Carbon dioxide and electrons are released and a small amount of ATP is generated.
105
Where does the ETC occur?
In the inner mitochondrial membrane
106
What is the purpose of the mitochondria?
It is the energy power plant of the cell
107
What is required for the ETC to create ATP?
As long as oxygen is available (aerobic pathway) ATP will continue to be produced.
108
What carries the electrons from the first 3 steps of the ETC?
Coenzymes
109
What is the final pathway in creating energy?
The ETC
110
Approximately how much ATP produced from the catabolism of glucose is produced by the ETC?
90%
111
What is the end product of glucose catabolism for glycolysis?
ATP and electrons
112
What is the end product of glucose catabolism for pyruvate to acetyl CoA?
Electrons and CO2
113
What is the end product of glucose catabolism for the Krebs Cycle?
ATP, electrons, and CO2
114
What is the end product of glucose catabolism for the ETC?
ATP and H2O
115
What 3 ways can the fat we get from food be used?
1. To provide fat to cells for different essential functions
2. To provide energy
3. To be used for storage
116
What cells cannot metabolize fat?
Nerve cells and RBCs
117
Is the breakdown of fat an aerobic or anaerobic process?
Aerobic process happening in the mitochondria of cells
118
What is fat broken down into?
To glycerol and fatty acids
119
How is glycerol broken down and converted?
Glycerol is easily converted to pyruvate, which can then be converted to either glucose or back to pyruvate and to acetyl CoA. (3 carbon molecules)
120
How are fatty acids broken down and converted?
Fatty acids are taken apart 2 carbons at a time in a series of aerobic reactions known as fatty acid oxidation (beta oxidation)
121
What is beta oxidation (fatty acid oxidation)?
The metabolic breakdown of fatty acids to acetyl CoA where each 2-carbon fragment splits off and combines with a molecule of CoA to make acetyl CoA.
122
What is released each time a 2-carbon fragment breaks off from a fatty acid during beta oxidation?
A little energy.
123
What happens if proteins are consumed in excess?
1. Some can be converted into glucose or fatty acids
| 2. some can be used as a source of energy
124
What is the first step in using protein as energy?
Deamination
125
What is deamination?
The act of removing the amino group (NH2) from the AA, which produces NH3 (ammonia)
126
What is a product of deamination?
Ammonia, which the liver combines with CO2 to convert it into the waste product Urea, which is excreted by the kidneys as urine.
127
What is the second step in using protein as energy?
Keto acids to...
1. Pyruvate can be converted into glucose or convert to Acetyl CoA (glucogenic)
2. Acetyl CoA can be converted into fatty acids for stores or continue into the TCA cycle to make ATP (ketogenic)
3. Some can enter directly into the TCA cycle without being converted in Acetyl CoA first (gluogenic)
128
What is the body's main mechanism for excreting unused nitrogen?
Excreting it as urea in urine
129
What happens when we consume excess amounts of the macronutrients (feasting)?
The excess nutrients will be converted to the storage form of energy - fat.
When energy is not needed the acetyl CoA molecules can be converted to fatty acids (instead of entering the krebs cycle) since all the nutrients can be converted to Acetyl CoA and it can be converted to fatty acids, then anything consumed in excess will be converted to triglycerides and stored as adipose tissue
