Lessons 5-7 Biochemistry Flashcards
4 Main Classes of Macromolecules
- Carbohydrates
- Lipids
- Proteins
- Nucleic Acids
What are macromolecules?
Large organic molecules composed of thousands of smaller molecules covalently bonded together
Macro = large
What is a monomer?
The small molecular subunits that make up macromolecules
Monomer of carbohydrates
Glucose (simple sugar)
Monomer of lipids
Glycerol and 3 fatty acids
Monomer of proteins
Amino acids
Monomer of nucleic acid
Nucleotides
What makes up Polymers?
Monomers link together in long chains to form polymers
Carbs, proteins, lipids and nucleic acids are all polymers
The process where multiple monomers link to form a polymer
Polymerization
Dehyrdration synthesis reactions that assemble complex carbs is an example of what process?
Polymerization
What elements do carbs contain?
Carbon, oxygen and hydrogen
Function of carbs (3)
- Energy
- Structure
- Cell to cell communication
carbs are the primary energy molecules of life (fuel source) and make up the cell wall in plants (structure/building blocks)
3 types of carbs
(from simple to complex)
- Monosaccharides
- Disaccharides
- Polysaccharides
Suffixes “saccharide” and “ose” mean sugar and refer to carbs
What are monosaccharides?
Single sugars, are the primary energy molecules of life (especially glucose)
Examples of monosaccharides
Glucose, fructose, galactose
Monosaccharide chemical structure
Carbon backbone with hydroxyl groups attached
Location of hydroxyl groups dependent on different types of bonds
What are monosacchardies classified by
- The location of the carbonyl group
- The number of carbons in the molecules backbone
Location is either aldehyde or ketone
What are the 2 groups of monosaccharides?
- Aldoses (aldehyde similar)
- Ketoses (ketone similar)
Aldoses structure
- Carbonyl group at the end
- Formed from aldehydes
Ex. glucose
Ketoses structure
- Carbonyl group in the middle
- Formed from ketons (usually on the #2 carbon)
Ex. fructose
What is the molecular structure of monosaccharides when dry?
Sugars form linear chains
Linear = dry
What is the molecular structure of monosaccharies when dissolved in water?
Sugars form ring structures
5-sided ring = fructose
6-sided ring = glucose, galactose
How are ring structures formed?
The hydroxyl and carbonyl groups in the same molecule interact, which causes the chain of carbon atoms to fold into a ring.
What are the 2 possible arrangements of the -OH group in glucose rings
2 different arrangements = isomers
- α-glucose
- β-glucose
OH group on carbon 1 points down
α-glucose
OH group on carbon 1 points up
β-glucose
What are isomers
Isomers are molecules with the same chemical formula, but a different arrangement of atoms (different structure).
T/F - glucose, fructose and galactose are isomers of each other
True - they have the same chemcial formula but different molecular structures
What is the significance of isomers
Different arrangements of atoms can result is molecules with different shapes and thus, different functions.
Which is easier for humans to digest: α-glucose or β-glucose
a glucose
T/F - molecular structure determines function
True
T/F - starches are more difficult to digest then cellulose
False - starches are easier to digest then cellulose because starches are made of α-glucose, meanwhile cellulose is made of β-glucose
What are disaccharides?
Double sugars (2 monosaccharides covalently bonded together via dehydration synthesis)
What are disaccharides made of?
Made of 2 monosaccharides covalently bonded by dehydration synthesis
What reaction bonds monosaccharides to form disacchardies?
Dehydration synthesis
What is the name of the covalent bond formed between 2 monosaccharides?
Gylcosidic bond/linkage
What are 3 examples of disaccharides?
Maltose, sucrose, lactose
What two monosaccharides make up maltose?
Glucose + Glucose
What two monosaccharides make up sucrose?
Glucose + Fructose
What two monosaccharides make up lactose?
Galactose + Glucose
Are glycosidic linkages strong or weak?
Glycosidic bonds are weak and can be broken without using too much energy
What is the primary function of disaccharides?
Energy source
What type of bond/linkage forms between carbs?
Glycosidic bond/linkage
What are the 2 types of glycosidic linkage?
- α- glycosidic linkage
- β- glycosidic linkage
What direction is the bond of β- glycosidic linkages oriented?
upwards and downwards
What direction is the bond of α- glycosidic linkages oriented?
downwards
What are polysaccharides
Are complex carbohydrates composed of 100’s of monosaccharides held together by glycosidic linkages
Aka many sugars - ex. polymer –> polysaccharide
Molecular structure of polysaccharides
Linear (unbranched) OR branched chains
Function of polysaccharides
- Energy storage
- Structural support
How is polysaccharide function determined?
Determined by type of monomers and the positions of glycosidic linkages
T/F - the main monosaccharide is glucose and glucose is the monomer for building complex carbohydrates (also known as polysaccharides)
True
What are the 4 types of polysaccharides?
- Starch (amylose)
- Glycogen (“animal starch”)
- Cellulose
- Chitin
What is the function of starch?
Energy storage
Ex. storage form of glucose in plants
Does Starch contain a-glucose or b-glucose?
a-glucose units linked by glycosidic bonds
What type of linkage is in starch and which direction are they oriented?
a-glycosidic linkages oriented downwards
The glycosidic bonds point in the same direction (downwards)
What is the function of glycogen?
Energy storage
What is the molecular structure of glycogen?
Branched chain of a-glucose subunits
What produces glycogen?
Produced by animals
Where is glycogen stored?
Stored in muscles and liver
Muscles and liver can recover glucose by hydrolysis when sugar is needed
How is glucose recovered from glycogen?
By hydrolysis when sugar is needed in the muscles and liver
Hydrolysis breaks bonds so energy can be released/used
What is the function of cellulose
Structural support
What produces cellulose
Produced by plants for cell walls
T/F - cellulose is the most common polysaccharide on Earth
True
What type of linkages are in cellulose
Alternating b-glycosidic linkages (up/down)
Made up of b glucose monomers
T/F - humans have a specific enzyme to digest cellulose
False - it is a form of insoluble fiber
Function of chitin
Structural support
Difference between Chitin and cellulose
Chitin contains nitrogen (animal cellulose - similar structure but contains nitrogen)
What type of linkages make up chitin?
b-glycosidic linkages
Examples of where chitin is found
Exoskeletons in arthropods and cell wall in fungi
What elements do nucleic acids contain
Carbon, hydrogen, oxygen, nitrogen and phosphorus
What is the monomer of nucleic acids?
Nucelotide
Function of nucleic acids
- Used by all organisms to store genetic information
- Provide the blueprint for protein assembly
What are the 2 types of nucleic acids?
- DNA (deoxyribonucleic acid)
- RNA (ribonucleic acid)
What does nucleotide consists of
- A nitrogenous base
- Pentose sugar (five sided sugar)
- Phosphate group
What is the portion of a nucleotide without the phosphate group called?
Nuceloside
What are the 2 types of nitrogenous bases
- Pyrimidines
- Purines
What do pyrimidines contain?
Cytosine (C), thymine (T) and uracil
Molecular structure of pyrimidines
Single ring structure
What does purines contain
Adenine and Guanine
What is the molecular structure of purines?
2 ring structures fused together
What is the similarity between pyrimidines and purines
Both types of bases have a high nitrogen content
Memory trick - 2 pure Ag rings
What are the two types of sugars in nucleic aicds?
Deoxyribose and ribose
What type of sugar is in DNA
Deoxyribose
What type of sugar is in RNA
Ribose
What is a polynucleotide?
Many nucleotides linked together in a long chain
What is the polymer of nucleic acids called?
Polynucleotides
Nucleic acids are polymers called polynucleotides
What are the “rungs” of the DNA “ladder” held together by? (what bond)
Hydrogen bonds
What type of bond joins adjacent nucleotides?
Covalent bonds
Between what groups of the nucleotide do the covalent bonds form between adjacent nucleotides?
The -OH group on the sugar of one nucleotide and the phosphate group on another nucleotide
How do adjacent nucleotides join via covalent bonds?
The -OH group on the sugar of one nucleotide and the phosphate group on another nucleotide
What forms the sugar-phosphate backbone of nucleic acid chains?
The covalent bonds between -OH group on the sugar of one nucleotide and the phosphate group on another nucleotide
What do the covalent bonds between -OH group on the sugar of one nucleotide and the phosphate group on another nucleotide form?
The sugar-phosphate backbone of nucleic acid chains
What type of bond/linkage forms between nucleic acids?
phosphodiester bonds
What is the function of the phospholipid bilayer/cell membrane?
Control the passage of molecules into and out of the cell
What is the cell membrane made up of?
A phospholipid bilayer
Bilayer = double layer
T/F - the phospholipid bilayer is selectively permeable
True - this means it allows some substances to cross and others cannot (selective)
What does the fluid mosaic model state?
States that the plasma membrane is a fluid strcutre with a “mosaic” of various lipids and proteins embedded in it.
What is embedded in the fluid mosaic model?
Lipids and proteins
What are the 4 main components of the cell membrane?
- Phospholipids
- Cholesterol
- Membrane proteins
- Carbohydrate groups
Where is the extra cellular fluid located?
Outside the cell
Where is the cytoplasm located?
inside the cell
Where is glycoprotein located?
Carbs attached to proteins on the extracellular side of the membrane
See diagram (lesson 7 pg.1)
Where is the glycolipid located?
carbs attched to lipids on the extracellular side of the membrane
See diagram (lesson 7 pg.1)
Where is the peripheral protein located?
On the inner or outer surface of the phospholipid bilayer, NOT embedded in its hydrophobic core
See diagram (lesson 7 pg.1)
Where is the integral protein located?
Embedded in the phospholipid bilayer: MAY or MAY NOT extend through both layers
See diagram (lesson 7 pg.1)
Where is cholesterol located in the cell membrane?
Tucked between the hydrophobic tails of the membrane phospholipids
See diagram (lesson 7 pg.1)
Where is the protein channel located?
See diagram (lesson 7 pg.1)
Where is the hydrophilic heads of the phospholipid bilayer located
See diagram (lesson 7 pg.1)
**Phospholipids = main fabric of the membrane
Where is the cytoskeletal filaments located?
See diagram (lesson 7 pg.1)
in the cell membraneWhat are phospholipds?
Make up the main structure of the cell membrane
What is a characteristic of phospholipds?
They are amphipathic
amphipathic = have both hydrophobic and hydrophilic regions
What makes phosphilipds well suited for their role in the cell membrane?
They are amphipathic
What is the hydrophilic region of a phospholipd?
Hydrophilic head
What is the hydrophobic region of a phospholipid?
Hydrophobic fatty acid tails
Which direction do the hydrophilic heads of a phospholipid face?
Face outward and interact with water
Which direction do the hydrophobic heads of a phospholipid face?
Face inwards and interact with each other
How does cholesterol minimize the effects of temperature on membrane fluidity?
- reduces membrane fluidity at moderate temps
- Hinders solidifcation at low temps
What is the function of cholesterol in the cell membrane?
- Acts as a membrane stabilizer
- Minimizes the effects of temperature on membrane fluidity
What is the second major component of cell membranes?
What part of the cell membrane does this: creates space for membrane when particles pack close together in cold temps
Cholesterol
Membrane proteins
What are the 2 types of membrane proteins
- Peripheral proteins
- Integral proteins
Where are peripheral proteins found?
On the outside/inside surfaces of the membrane
ARE NOT EMBEDDED
Where are integral proteins located?
EMBEDDED into the lipid bilayer
What are integral proteins that span the membrane also called?
Transmembrane proteins
What type of protein can penetrate the hydrophobic core of the phospholipid bilayer and span the membrane?
Integral proteins
What do the hydrophobic regions of an integral protein conist of?
One or more stretches of non-polar amino acids
What structure are the non-polar amino acids of the hydrophobic regions of an integral proteins often coiled into?
a-helix
What are the 4 major functions of membrane proteins?
- Transport
- Receptor
- Enzyme
- Anchor/attachment
Where are membrane carbohydrates located?
Found on the outside surface of cell membranes
What are glycoproteins
Carbs bonded to proteins
What are glycolipids?
Carbs bonded to lipids?
What is the function of membrane carbohydrates?
Act as identification markers which allows cells to recognize each other
Why are identification markers important in the cell membrane?
Allows cells to recognize each other
What does the fluidity of the lipid bilayer depend on?
Depends on how tightly the individual phospholipid molecules can pack together
What are the 3 major factors that influence membrane fluidity/how tightly the individual phospholipid molecules can pack together?
- Fatty acid tails
- Temperature
- Cholesterol
How does saturated fatty acid tails influence membrane fluidity?
Saturated fatty acid tails have a straight shape so phospholipids can pack together MORE TIGHTLY
What shape do saturated fatty acid tails have?
Straight shape
What shape do unsaturated fatty acid tails have?
Bent shape (due to double bonds)
How does unsaturated fatty acid tails influence membrane fluidity?
Phospholipids are more LOOSELY PACKED due to bent shape caused by double bonds
Which have more fluidity: membranes rich in unsaturated or saturated fatty acid tails?
Membranes rich in unsaturated fatty acid tails have more fluidity
Due to phospholipids being more loosely packed
How does temperature influence membrane fluidity?
Temperature affects how the phospholipids move and how close together they are found?
How does cold temperature effect phospholipids and fluidity?
- Phospholipids are close together
- Less fluid
How does hot temperatures affect phospholipids and fludiity?
- Phospholipids are farther apart
- More fluid
What does the temperature at which a membrane solidifes depend on?
The types of fatty acids
What happens to the fluidity of a membrane when the temperature is cold with no chloesterol?
- Rigid
- Not as fluid/flexible
- May break
What happens to the fluidity of a membrane when the temperature is hot with no chloesterol?
- Too fluid/flexible
- Won’t hold shape
How does cholesterold influence membrane fluidity at low temperatures?
Cholesterol prevents phospholipids from packing together too tightly
ENSURES MEMBRANE IS STILL FLUID
How does cholesterol influence membrane fluidity at high temperatures?
Cholesterol limity the level of fluidity by limiting the movement of phospholipds
KEEPS THE MEMBRANE INTACT
Whay is a-glucose/starch easier to digest?
Branched structure (easier to break/digest)
Why is cellulose/b-glucose more difficult to digest?
Stacked/condensed structure (harder to break/more difficult to digest)
