CH 5 Lecture Mastery Flashcards
What are macromolecules
-Large molecules held together by covalent bond
-Made of SPONCH elements
Macromolecules are generally
nonpolar
Most macromolecules are ______, built from ______
Most macromolecules are polymers, built from monomers
A long molecule made up of repeating monomers linked by covalent bonds.
Polymer
What macromolecule is not formed by polymerization?
Lipids
(While lipids are formed through dehydration synthesis, they are not polymers in the traditional sense because they are not made of repeating monomeric units.)
What molecule is necessary for hydrolysis to occur?
water
What is Polymerization?
-Enzymes (usually proteins) catalyze the formation of polymers through dehydration synthesis reaction.
-It forms water as a byproduct
-It requires enzymes
-It forms covalent bonds
Explain how polymerization reactions contribute to the structure and function of biological macromolecules.
Answer: Polymerization forms complex structures like proteins, which have specific shapes and functions, or carbohydrates that provide energy and structural support. The sequence and type of monomers affect the final polymer’s properties.
Given the polymerization of glucose molecules to form cellulose, how many water molecules are produced when 100 glucose molecules link together?
Answer: 99 water molecules are produced. Each bond formation between glucose units releases one water molecule.
A chain of 10 amino acids undergoes hydrolysis. How many water molecules are needed to completely break down this polypeptide into individual amino acids?
Answer: 9 water molecules are needed. Hydrolysis requires one water molecule to break each peptide bond, and a polypeptide with 10 amino acids has 9 peptide bonds.
Describe the process of forming a disaccharide from two monosaccharides using dehydration synthesis. What byproduct is formed?
Answer: During dehydration synthesis, two monosaccharides (e.g., glucose + fructose) bond together to form a disaccharide (e.g., sucrose) by releasing a water molecule as a byproduct.
What types of biological molecules are formed through polymerization? Give examples.
Biological macromolecules formed through polymerization include proteins (formed by amino acids), carbohydrates (e.g., polysaccharides like starch formed by monosaccharides), and nucleic acids (e.g., DNA and RNA formed by nucleotides).
Why is polymerization considered a chemical reaction? What type of bonds are formed?
Polymerization is a chemical reaction because it involves the breaking and forming of covalent bonds between monomers, resulting in the formation of large, complex molecules (polymers).
Explain the role of enzymes in polymerization. Why are they important?
Enzymes act as catalysts in polymerization, speeding up both dehydration synthesis and hydrolysis by lowering the activation energy needed for the reactions to occur.
Compare and contrast dehydration synthesis and hydrolysis. What role does water play in each process?
Dehydration synthesis removes water to join monomers, forming polymers. Hydrolysis adds water to break polymers into monomers. Water is a byproduct in dehydration synthesis, whereas it is a reactant in hydrolysis.
What are the monomers of carbohydrates?
Saccharides (Monosaccharides)
What type of isomers are glucose and fructose?
Structural isomers
Compare starch and cellulose. What role does each play in the human body?
Starch: Used as an energy source (digestible by humans)
Cellulose: Provides structural support in plants (not digestible by humans)
How does dehydration synthesis form disaccharides and polysaccharides?
By removing a water molecule to form a glycosidic linkage
Describe the process of dehydration synthesis in the formation of disaccharides.
Dehydration synthesis, also known as a condensation reaction, involves the joining of two monosaccharides with the removal of a water molecule, resulting in the formation of a glycosidic bond.
How does the branching structure of glycogen benefit animals in terms of energy storage and mobilization?
The highly branched structure of glycogen allows for rapid release of glucose units when energy is needed, as enzymes can simultaneously work on multiple branches, facilitating quick mobilization of stored energy.
What is the role of waxes in plants and animals?
In plants, waxes prevent water loss by forming a protective layer on the surface of leaves and stems.
In animals, waxes provide water repellency, such as in the coating of feathers and fur, and help prevent water loss (e.g., in insects or animals living in dry environments).
How do steroid hormones differ structurally from other lipids?
Steroid hormones have a four-ring carbon structure that is different from the long chains or branched structures of other lipids like fats. The rings allow them to have various functional groups attached, which is key for their role as hormones in signaling.
Why do plants store energy as starch, while animals store energy as fat?
Plants store energy as starch because they are relatively immobile and can afford to have a bulkier form of energy storage.
Animals store energy as fat because it is more compact and efficient for long-term energy storage, which is important for mobility.
What is the function of cholesterol in animal cell membranes?
Cholesterol is essential for maintaining membrane fluidity. It fits between phospholipids in the membrane, preventing it from becoming too rigid in cold temperatures and too fluid in warm temperatures. This helps stabilize the cell membrane.
How does the structure of saturated and unsaturated fats affect their physical state at room temperature?
Saturated fats have no double bonds between carbon atoms, allowing them to pack tightly together. This structure makes them solid at room temperature (e.g., butter, lard).
Unsaturated fats have one or more double bonds, causing kinks in their carbon chains. These kinks prevent the molecules from packing closely, making them liquid at room temperature (e.g., olive oil, fish oils).
Describe the role of phospholipids in the cell membrane.
Phospholipids are crucial for forming the phospholipid bilayer in the cell membrane. Their hydrophilic heads face outward towards the aqueous environment, while their hydrophobic tails face inward, away from the water. This structure creates a semi-permeable membrane that protects the cell and allows selective passage of molecules.
______ are used for energy storage, while ______ form the structural basis of cell membranes.
Triglycerides are used for energy storage, while phospholipids form the structural basis of cell membranes.
Composed of one glycerol molecule linked to three fatty acid chains via ester linkages.
Triglyceride (Fat)
Composed of one glycerol molecule linked to two fatty acid chains and a phosphate group (with a hydrophilic “head” and hydrophobic “tails”).
Phospholipid
Why are human sex hormones considered lipids?
Human sex hormones (like estrogen and testosterone) are considered lipids because they are derived from cholesterol, which is a type of lipid. They are hydrophobic molecules and share the structural feature of steroid rings, which is characteristic of lipids.
What characteristic makes lipids hydrophobic?
Lipids are hydrophobic due to their non-polar hydrocarbon regions, which do not interact well with water molecules. This is because the majority of lipids are made up of long carbon chains that are primarily non-polar.
What elements make up the monomers of proteins?
Carbon, hydrogen, nitrogen, oxygen, sulfur (SONCH)
Describe the structure of an amino acid.
Consists of an amino group, a carboxyl group, a hydrogen atom, and a variable R group attached to an alpha carbon.
What type of bond links amino acids together?
Peptide bonds.
How are peptide bonds formed?
Through dehydration synthesis between the carboxyl group of one amino acid and the amino group of another.
What structure is the Linear sequence of amino acids.
Primary
What causes alpha helices and beta-pleated sheets to form in secondary structure?
Hydrogen bonding between amino acids.
The tertiary protein structure involves
3D shape due to R-group interactions.
Explain how R-group interactions contribute to tertiary structure.
Interactions such as hydrophobic interactions, ionic bonds, hydrogen bonds, and disulfide bridges.
What distinguishes quaternary structure from the other levels?
Involves the assembly of multiple polypeptide chains.
How does the hydrophobicity of side chains influence protein folding?
Hydrophobic side chains typically fold inward, away from the aqueous environment, helping stabilize the protein’s structure.
What factors can cause a protein to denature?
Changes in pH, temperature, or exposure to chemicals.
Explain why denaturation affects protein function.
It disrupts the protein’s 3D shape, preventing it from binding to other molecules properly.
How does a protein’s shape determine its function?
The specific shape allows proteins to bind precisely with other molecules, enabling specific biological activities.
Describe the impact of a change in the amino acid sequence on protein structure and function.
It can alter the protein’s folding, potentially leading to loss of function or malfunction.
Where would you expect to find hydrophobic amino acids in a folded protein?
In the interior of the protein, away from water.
What are the components of a nucleotide?
Nitrogenous base, sugar, and phosphate group.
What elements are found in nucleic acids?
Phosphorus, oxygen, nitrogen, carbon, hydrogen (PONCH).
What are the two types of nucleic acids?
DNA and RNA.
How do DNA and RNA differ in their nitrogenous bases?
DNA has thymine (T), while RNA has uracil (U).
Describe the structural differences between DNA and RNA.
DNA is double-stranded; RNA is single-stranded.
DNA has deoxyribose sugar; RNA has ribose sugar.
What is gene expression?
The process of converting genetic information from DNA to proteins via RNA.
Explain the flow of genetic information.
DNA → RNA → Protein.
What is the role of mRNA in protein synthesis?
Carries genetic instructions from DNA to ribosomes.
How do tRNA and rRNA contribute to protein synthesis?
tRNA brings amino acids; rRNA forms part of ribosomes that build proteins.
Where does protein synthesis occur in eukaryotic cells?
In ribosomes within the cytoplasm.
What type of bond links nucleotides in a polynucleotide?
Phosphodiester bonds.
Describe complementary base pairing in DNA.
Adenine pairs with thymine (A-T), cytosine pairs with guanine (C-G).
What impact could a mutation in a gene have on protein function?
It can alter the amino acid sequence, potentially affecting the protein’s structure and function.
What are the three main components of cell theory?
Cells are the basic unit of life,
all living organisms are made of cells,
and cells come from pre-existing cells.
What are the basic components found in all cells?
Cell membrane, cytoplasm, DNA, and organelles.
No membrane-bound organelles, single-celled (e.g., bacteria).
Prokaryotic
Membrane-bound organelles, can be multicellular (e.g., plants, animals).
Eukaryotic
Differentiate between prokaryotic and eukaryotic cells.
Prokaryotic: No membrane-bound organelles, single-celled (e.g., bacteria).
Eukaryotic: Membrane-bound organelles, can be multicellular (e.g., plants, animals).
What is the primary function of organelles in eukaryotic cells?
Specialized structures that perform specific functions within the cell.
Why are prokaryotic cells considered simpler than eukaryotic cells?
They lack membrane-bound organelles and are generally smaller and less complex.
How does the nucleotide sequence influence protein synthesis?
It determines the amino acid sequence of the resulting protein.
What impact could a mutation in a gene have on protein function?
It can alter the amino acid sequence, potentially affecting the protein’s structure and function.
What is the primary function of the cell membrane?
It acts as a barrier, regulating what enters and exits the cell while protecting it from toxins and allowing waste removal.
What is the structure of the cell membrane?
It is a phospholipid bilayer with hydrophilic heads facing outward and hydrophobic tails facing inward. It also contains proteins (for support and transport) and sterols (for extra stability).
What is the function of the nucleus?
The nucleus stores and protects DNA and is involved in the early stages of protein synthesis.
What is the role of nuclear pores?
They allow information (RNA, proteins) to pass between the nucleus and the cytoplasm.
What is chromatin?
Chromatin is a complex of DNA and proteins that condenses into chromosomes during cell division.
What is the primary function of the endomembrane system?
It synthesizes, modifies, transports, and stores macromolecules (proteins, lipids, carbohydrates).
What is the difference between rough ER and smooth ER?
Rough ER has ribosomes and makes proteins.
Smooth ER lacks ribosomes and makes lipids and carbohydrates; it also detoxifies harmful substances.
______ ER has ribosomes and makes proteins.
Rough
______ ER lacks ribosomes and makes lipids and carbohydrates; it also detoxifies harmful substances.
Smooth
What does the Golgi apparatus do?
It modifies, packages, and ships macromolecules (proteins, lipids, carbs) received from the ER.
What are vesicles and vacuoles?
Vesicles: Transport molecules inside the cell and to the membrane for secretion.
Vacuoles: Store water, nutrients, or waste (larger in plant cells).
How do vesicles help in cell communication and transport?
They merge with the plasma membrane to release macromolecules (waste, signaling molecules) outside the cell through exocytosis.
What is the function of ribosomes?
Ribosomes are the sites of protein synthesis where mRNA is translated into proteins.
What are ribosomes made of?
rRNA (ribosomal RNA) and proteins.
Are ribosomes membrane-bound?
No, they do not have membranes.
Where are ribosomes located in the cell?
Free-floating in the cytoplasm (making proteins for the cell).
Attached to the rough ER (making proteins for export).
What is the function of mitochondria?
They generate ATP (energy) by breaking down glucose through cellular respiration.
What is the function of chloroplasts?
Found in plant cells, they convert sunlight into chemical energy (ATP & sugars) through photosynthesis.
What is ATP and why is it important?
ATP (adenosine triphosphate) is the cell’s energy currency, used for growth, repair, and movement.
What does the endosymbiosis theory propose?
Mitochondria and chloroplasts originated as free-living prokaryotes that were engulfed by larger cells, forming a symbiotic relationship.
What is the function of flagella?
Flagella are long, whip-like structures that move in a snake-like motion to propel the cell.
What is the function of cilia?
Cilia are short, hair-like projections that move like oars and help with movement and environmental interaction.
What is the function of the cell wall?
Provides structure, support, protection, and water regulation in plants, fungi, and algae.
What is the extracellular matrix (ECM)?
Found in animal cells, it provides support and communication between cells.
What is the cell wall made of in different organisms?
Plants: Cellulose.
Fungi: Chitin.
Algae: Varies by species.
Cell Junctions (Cell-to-Cell Connections)
In Plant Cells
What are plasmodesmata?
Tubes connecting cytoplasm between plant cells, allowing for communication and transport.
In Animal Cells
What are tight junctions?
Seal neighboring cells together to prevent leakage (e.g., intestines).
What are desmosomes?
Anchor cells together like spot welds, providing mechanical strength (e.g., in skin).
What are gap junctions?
Protein channels that connect neighboring cells, allowing direct exchange of molecules and communication (like plasmodesmata in plants).
Why do mitochondria and chloroplasts have double membranes?
This supports the endosymbiosis theory, suggesting they were engulfed by a larger cell and retained their original membrane while acquiring a second membrane.
How do cells regulate their internal environment using the cell membrane?
The cell membrane is selectively permeable, allowing only specific substances to enter and exit through transport proteins, lipid diffusion, or vesicle fusion (exocytosis & endocytosis).
