1 , 4 Flashcards
What is the common genetic flow process found in all living cells?
DNA → RNA → Protein
n what form is genetic information stored in all living organisms?
DNA
T/F: Viruses are considered living organisms
False
How do viruses reproduce if they are not considered living?
They use the host cell’s machinery to replicate
What are proteins made of?
Proteins are made of 20 different types of amino acids
T/F: Amino acids are linked by hydrogen bonds in a polypeptide
False: Amino acids are linked by covalent peptide bonds
What is essential for the folding of proteins?
Peptide Backbone Hydrogen Bonds
What are the two types of secondary protein structures?
alpha helix & beta pleated sheet
α-Helix are formed by ______ bonding between every ___ amino acid
hydrogen ; 4th
How are β-pleated sheets formed?
By hydrogen bonding between different areas of the polypeptide backbone, forming a zig-zag structure
What is tertiary protein structure?
The full 3D shape of a protein, including α-helices, β-sheets, and random coils
Tertiary structure only involves α-helices
False. It involves α-helices, β-sheets, and other elements
Which structure determines the functional domains in a protein
Tertiary structure
What is the quaternary structure of a protein?
The association of multiple polypeptide chains to form a functional protein
T/F: All proteins have quaternary structure
False. Only proteins with more than one polypeptide chain have quaternary structure
Give an example of a protein with quaternary structure
Hemoglobin
Why is protein folding important?
Proper folding is crucial for protein function, and misfolding can lead to diseases
Misfolded proteins cause diseases like….
Cystic Fibrosis and Alzheimer’s
T/F: The 3D structure of a protein does not affect its function
False. Protein function is directly related to its 3D structure
What determines a protein’s final structure?
The amino acid sequence
What kind of bonds hold a ligand in a protein’s binding site?
Non-covalent bonds
(hydrogen bonds, electrostatic attractions, van der Waals forces)
T/F: Protein-ligand binding is random
False; it is highly specific
What is the function of an enzyme?
Enzymes catalyze reactions by lowering the activation energy
T/F: Most drugs inhibit enzymes by blocking the active site.
True
What type of enzyme is lysozyme?
An enzyme that breaks down bacterial cell walls
What is an allosteric enzyme?
An enzyme with multiple binding sites that influence each other
T/F: Phosphorylation always activates a protein
False. Phosphorylation can either activate or deactivate a protein
GTP-binding proteins act as…
On-off switches
(GTP = ON, GDP = OFF)
What powers motor proteins like myosin and actin?
ATP hydrolysis
T/F: Motor proteins move bidirectionally
False; Motor proteins move unidirectionally due to irreversible steps
What is the sequence from non-living to living structures in organisms?
Atoms → molecules → organelles → cells → tissues → living organisms
T/F: Cells can only grow and reproduce, but they cannot respond to environmental changes
False; Cells can also respond to environmental changes
What type of reaction forms a peptide bond between amino acids?
A condensation reaction
T/F: Small changes in amino acid sequence, such as in Sickle Cell Disease, can significantly affect protein function
True
What advantage does quaternary structure provide to proteins
It allows for the construction of large, complex proteins with cooperative functional properties
How does lysozyme lower the activation energy of the reaction?
Lysozyme creates a microenvironment where the polysaccharide chain is distorted, weakening its bonds and facilitating hydrolysis
Name a protein that relies on a tightly bound metal atom for its function
Hemoglobin, which has an iron atom bound to oxygen in each heme group
T/F: Phosphorylation is a reversible mechanism used to control protein activity
True
What does “allosteric” mean in the context of proteins?
“Allosteric” means “other shape,” referring to a protein having multiple binding sites that influence each other
What causes the symptoms of viral infections like a cold sore?
The symptoms are caused by the lysis (breaking open) of cells, as seen in herpes simplex virus infections
What is lysis?
the breakdown of a cell by rupture of the cell wall or membrane
T/F: Higher organisms are made up of a community of cells derived from multiple founder cells
False; Higher organisms are made of communities of cells derived from the division of a single founder cell
How do cells convert energy?
Cells convert energy from one form to another through processes like cellular respiration in mitochondria
According to the cell theory, how did cells first arise?
Living cells are formed by the division of pre-existing cells
Prokaryotic cells have a nucleus while eukaryotic cells do not
False; Prokaryotic cells lack a nucleus, while eukaryotic cells have a defined nucleus
Name two key differences between prokaryotic and eukaryotic cells
- Prokaryotic cells lack membrane-bound organelles, while eukaryotic cells contain membrane-bound organelles
- Prokaryotic cells are generally smaller in size, while eukaryotic cells are larger.
Which of the following is not a feature of prokaryotic cells?
A) Single, circular DNA molecule
B) Ribosomes
C) Mitochondria
C) Mitochondria
What is an example of a prokaryotic organism?
Bacteria
T/F: Eukaryotic cells are typically found in animals, plants, and fungi
True
Which type of cells undergo mitosis?
Eurkaryotic
What is the main function of the nucleus in eukaryotic cells?
The nucleus stores and protects the cell’s genetic material (DNA) and coordinates cell activities like growth and reproduction
T/F: The mitochondria are responsible for protein synthesis
False; The mitochondria are responsible for energy production (ATP), while ribosomes are responsible for protein synthesis.
What is the function of the endoplasmic reticulum (ER)?
The ER functions in the synthesis of proteins (rough ER) and lipids (smooth ER)
The Golgi apparatus is primarily responsible for:
A) Breaking down cellular waste
B) Modifying, sorting, and packaging proteins and lipids
C) Synthesizing carbohydrates
B) Modifying, sorting, and packaging proteins and lipids
What is the primary function of the ribosomes?
Protein Synthesis
T/F: Chloroplasts are found in animal cells
False; Chloroplasts are found in plant cells
Chloroplasts are responsible for…
photosynthesis
What is the role of the cytoskeleton in a cell?
The cytoskeleton provides structural support, aids in cell movement, and helps in the organization of the cell’s components
Which organelle is known as the “powerhouse of the cell”?
The mitochondrion, because it produces energy in the form of ATP
Do prokaryotic cells have internal membrane-bound organelles?
No, prokaryotic cells do not have internal membrane-bound organelles
What is the main method of reproduction in prokaryotic cells?
A) Binary fission
B) Mitosis
C) Meiosis
A) Binary Fission
Name two organelles that are unique to plant cell
Chloroplasts and the cell wall
T/F: Both plant and animal cells contain a cell wall
False; only plant cells do
In which organelle does photosynthesis occur?
Chloroplast
Define “cytoplasm”
Cytoplasm is the gel-like substance within the cell membrane that contains organelles and the cytoskeleton
T/F: The plasma membrane is involved in regulating what enters and leaves the cell
True
What is the function of lysosomes in eukaryotic cells?
Lysosomes break down waste materials and cellular debris using enzymes
What structure controls the movement of substances in and out of the cell?
Plasma Membrane
What is the primary structure of a protein?
The sequence of amino acids in a polypeptide chain
How is the primary structure of a protein held together?
By covalent peptide bonds between amino acids
What is the secondary structure of a protein?
The local folding of the polypeptide chain into structures such as α-helices and β-pleated sheets
What type of bonds are involved in maintaining the secondary structure of proteins?
Hydrogen bonds between the backbone atoms of the polypeptide chain
Describe the α-helix
The α-helix is a spiral structure where the polypeptide chain twists, with hydrogen bonds forming between every fourth amino acid
What is the β-pleated sheet?
A folded, zig-zag pattern formed by hydrogen bonds between different segments of the polypeptide chain
What is the tertiary structure of a protein?
The full three-dimensional shape of a protein, including interactions between side chains (R groups) of the amino acids
Name at least two interactions that stabilize the tertiary structure of a protein
Hydrophobic interactions, hydrogen bonds, ionic bonds, and disulfide bridges
What is the quaternary structure of a protein?
The association of multiple polypeptide chains (subunits) into a functional protein complex
Give an example of a protein that has quaternary structure
Hemoglobin, which consists of four polypeptide subunits
What is the key difference between tertiary and quaternary structures?
Tertiary structure refers to the 3D shape of a single polypeptide, while quaternary structure refers to the assembly of multiple polypeptides into a complex
What is a protein complex?
A structure formed by multiple protein molecules (polypeptides) that interact and function together
How do proteins function in complexes within cells?
Proteins in complexes often work together to carry out complex functions such as DNA replication, cell signaling, or enzyme activity
What advantage does a protein complex have over individual proteins?
Protein complexes allow for cooperative interactions, greater regulation, and the ability to perform more complex tasks
What is an example of a protein complex in cells?
The ribosome, which is a complex of RNA and proteins that synthesizes proteins in the cell
Describe how hemoglobin functions as a protein complex
Hemoglobin is a complex of four polypeptide subunits, each capable of binding oxygen, allowing the cooperative transport of oxygen in the bloodstream
What is a ligand in the context of protein function?
A ligand is any molecule that binds specifically to a protein at a binding site
What types of bonds are involved in protein-ligand binding?
Non-covalent bonds, including hydrogen bonds, electrostatic attractions, and van der Waals forces
Where does a ligand bind on a protein?
A ligand binds to a specific binding site on the protein
What determines the selectivity of protein-ligand binding?
The shape and chemical properties of the binding site, which match the ligand like a “lock and key”
How do proteins achieve specificity when binding to other molecules?
Specificity is achieved by the precise fit between the ligand and the protein’s binding site, requiring many weak bonds to form simultaneously
What is the function of an antibody?
Antibodies bind to specific foreign molecules (antigens) and help neutralize or eliminate them from the body
How many binding sites does an antibody have?
An antibody typically has two binding sites, one on each arm of its Y-shaped structure
What makes the binding sites of antibodies versatile?
The variable regions of antibodies can be altered to bind specifically to a vast range of antigens
What part of the antibody is responsible for recognizing antigens?
The variable regions at the tips of the antibody arms are responsible for antigen recognition
What is the main role of enzymes in the cell?
Enzymes act as catalysts that speed up biochemical reactions by lowering the activation energy required for the reaction
What is a substrate in enzyme activity?
A substrate is the molecule upon which an enzyme acts, binding to the enzyme’s active site
How do enzymes lower the activation energy of a reaction?
Enzymes create a favorable environment for the reaction by positioning the substrate in a way that facilitates bond-breaking or bond-forming processes
What is the active site of an enzyme?
The active site is the specific region of the enzyme where the substrate binds and the reaction occurs
What is an example of an enzyme and its function?
Lysozyme, which breaks down bacterial cell walls by cleaving the bonds in polysaccharides
What is allosteric regulation in proteins?
Allosteric regulation is when a protein’s function at one site is affected by the binding of a regulatory molecule at a different site
What is the role of phosphorylation in protein regulation?
Phosphorylation is the addition of a phosphate group to a protein, which can trigger a conformational change that either activates or inactivates the protein
What are GTP-binding proteins, and how do they work?
GTP-binding proteins act as molecular switches; they are active when bound to GTP and inactive when bound to GDP
How does feedback inhibition control enzyme activity?
In feedback inhibition, the product of a metabolic pathway inhibits an enzyme involved earlier in the pathway, preventing overproduction of the product
How does nucleotide hydrolysis control motor proteins?
Motor proteins use the energy from ATP hydrolysis to perform large conformational changes that result in movement, such as muscle contraction
What is the significance of protein conformational changes?
Conformational changes in a protein can alter its activity, allowing it to perform its function, bind to other molecules, or be regulated
