Cell Biology Quiz: Cell Structures and Functions

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Questions and Answers

What is the primary function of the thylakoid membrane?

Storage of digestive enzymes.

Site of photosynthesis. (correct)

Location of water storage.

Site for protein synthesis.

Which part of the cell wall is primarily made of pectic acid?

Primary wall.

Cellulose matrix.

Secondary wall.

Middle lamella. (correct)

What is the main component of ribosomes?

Lipids and carbohydrates.

DNA.

Proteins only.

RNA and proteins. (correct)

What is the role of lysosomes in the cell?

To digest materials and cell components. Signup and view all the answers

What structure connects adjacent cells in a plant's cell wall?

Plasmaodesmata. Signup and view all the answers

What is the primary function of the Golgi apparatus?

Processing and packaging macromolecules. Signup and view all the answers

What surrounds a vacuole in a cell?

Tonoplast. Signup and view all the answers

Which component provides mechanical strength to a plant cell wall?

All of the above. Signup and view all the answers

What term is used for sugars with five-member rings?

Furanoses Signup and view all the answers

Which carbon in a monosaccharide becomes the anomeric carbon upon cyclization?

The carbonyl carbon Signup and view all the answers

What are the two possible configurations of the anomeric carbon called?

Anomers Signup and view all the answers

At equilibrium, what is the approximate percentage of the ß anomer of D-glucose in solution?

63.6% Signup and view all the answers

What type of stereoisomers differ in configuration at only one chiral center?

Epimers Signup and view all the answers

Which of the following terms refers to monosaccharides that have an -OH group replaced by another group?

Monosaccharide derivatives Signup and view all the answers

What are glycosides primarily formed from?

The condensation of a sugar and an aglycon Signup and view all the answers

What is the suffix used in naming glycosides derived from sugars?

-ide Signup and view all the answers

What role does pectin play in cancer cells?

It activates cell death pathways. Signup and view all the answers

Which of the following is a commercial use of agar?

As a thickening agent in liquids. Signup and view all the answers

What is agarose primarily used for?

Size-separation of large molecules. Signup and view all the answers

Which polysaccharide class is NOT part of agar?

Alginic acid Signup and view all the answers

What characteristic of agarose makes it useful for separation processes?

Relatively large pore size. Signup and view all the answers

What is the source of agar?

Red algae. Signup and view all the answers

What is the significance of carrageenan in food products?

It acts as a thickening and gelling agent. Signup and view all the answers

What is the primary structural role of agar polysaccharides in algae?

Cell wall support. Signup and view all the answers

Which of the following describes the structural composition of carrageenan?

It consists of alternating 3-linked-β-D-galactopyranose and 4-linked-α-D-galactopyranose units. Signup and view all the answers

What is a primary use of κ-carrageenan in food products?

To stabilize milk-casein products. Signup and view all the answers

From which type of seaweed is alginic acid primarily extracted?

Brown seaweed. Signup and view all the answers

What functional properties does alginic acid provide in the food industry?

It acts as a thickener and binder. Signup and view all the answers

What characteristic allows alginate to absorb water rapidly?

It is a linear copolymer with specific blocks. Signup and view all the answers

Which statement correctly describes the gel-forming properties of κ- and ι-carrageenan?

They form thermoreversible gels with appropriate counterions present. Signup and view all the answers

In addition to food applications, alginic acid is utilized in which of the following industries?

Textiles and paper manufacturing. Signup and view all the answers

What role does alginic acid play as a detoxifier?

It absorbs poisonous metals from the blood. Signup and view all the answers

What is the primary enzyme responsible for converting glucose to glucose 6-phosphate in liver and pancreatic cells?

Glucokinase Signup and view all the answers

What molecule is produced alongside glucose 6-phosphate during its conversion?

ADP Signup and view all the answers

Which enzyme catalyzes the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate?

Phosphofructokinase Signup and view all the answers

What happens to fructose 1,6-bisphosphate during the cleavage step of glycolysis?

It is split into dihydroxyacetone phosphate and glyceraldehyde-3-phosphate. Signup and view all the answers

Which of the following statements about hexokinase is true?

Hexokinase is inhibited by glucose 6-phosphate. Signup and view all the answers

What type of reaction does phosphoglucose isomerase catalyze?

Isomerization Signup and view all the answers

Which enzyme is responsible for the interconversion of glyceraldehyde-3-phosphate and dihydroxyacetone phosphate?

Phosphotriose isomerase Signup and view all the answers

What role does fructose 1,6-bisphosphate play in the glycolytic pathway?

It is a rate-limiting step in glycolysis. Signup and view all the answers

What is the primary factor that allows amino acids to exhibit optical activity?

Tetrahedral orientation around the α carbon Signup and view all the answers

Which type of amino acid is primarily found in protein molecules?

L stereoisomers Signup and view all the answers

At the pH of blood plasma (approximately 7.4), which form do carboxyl groups in amino acids predominantly exist as?

R-COO- Signup and view all the answers

Which of the following statements is true regarding the isoelectric point (pI) of amino acids?

At pI, amino acids possess no net charge. Signup and view all the answers

Which amino acid lacks an asymmetric carbon atom?

Glycine Signup and view all the answers

What charge do amino acids typically have in solutions where the pH is lower than their pKa values?

Positive net charge Signup and view all the answers

Which pair of groups present in amino acids behave as weak acids?

α-carboxyl group and α-amino group Signup and view all the answers

Which of the following accurately describes the solubility of amino acids in different solvents?

Amino acids are soluble in polar solvents like ethanol. Signup and view all the answers

Study Notes

Introduction to Biochemistry

Biochemistry is the branch of science that deals with the chemistry of life and living processes.
Biochemical studies include the chemical nature of living matter, its transformations in biological systems, and associated energy changes.
Biochemistry connects biology and chemistry by examining how complex chemical reactions and structures create life processes.

History of Biochemistry

Crucial biological concepts, including cell theory, Mendel's inheritance, and Darwin's theory of evolution, were developed during the 17th and 18th centuries.
A significant advance was Wohler's 1828 synthesis of urea, demonstrating that organic compounds can be created from inorganic materials.
Key figures in biochemistry include Louis Pasteur (1857), who studied fermentation, and Edward Buchner (1897) who extracted enzymes, initiating enzyme research.
The term "biochemistry" was first introduced by Neuberg in 1903.
Important milestones include the elucidation of the citric acid cycle and urea cycle(1930s-40s).
The discovery of the double helix structure of DNA by Watson and Crick (1953), was a key development.
Frederick Sanger's work on protein sequencing (1953) and nucleic acid sequencing (1977) further advanced the field.

Structure and Function of a Cell

Cells are the basic units of life, and are classified into prokaryotic and eukaryotic.
Prokaryotic cells lack a nucleus and are typically unicellular. Eukaryotic cells have a nucleus and are usually multicellular.
Prokaryotic cells reproduce via binary fission.

Cell Membrane

The cell membrane separates the cell from its external environment.
It is semipermeable, regulating the movement of substances in and out of the cell.
The cell membrane is a phospholipid bilayer with embedded proteins, involved in various processes.

Cytoplasm

The cytoplasm is the part of a cell enclosed by the cell membrane.
It contains various organelles, and the cytosol, which holds the components that are not within organelles.

Nucleus

The nucleus is the membrane bound organelle in eukaryotic cells with most of the cell's genetic material, like DNA.
It is crucial for directing protein synthesis.

Endoplasmic Reticulum (ER)

The endoplasmic reticulum (ER) is a vast network of interconnected, membranous, infolded, and convoluted sacs in the cytoplasm.
Rough ER is studded with ribosomes and plays a role in protein synthesis. It is folded into flattened sheets known as cisternae. The system sends synthesized proteins via vesicles to the Golgi apparatus.
Smooth ER lacks ribosomes, involved in the movement of molecules in the cell.

Mitochondria

Mitochondria are the ''powerhouses'' of the cell converting glucose to ATP. Mitochondria are spherical to rod-shaped organelles that have a double membrane.

Chloroplasts

Chloroplasts are the green plastids in plant cells.
They conduct photosynthesis.

Cell Wall

The cell wall encloses the cell membrane, giving shape and protection.
The primary cell wall, middle lamella, and secondary wall, form the structural components.

Ribosomes

Ribosomes, small organelles, are responsible for protein synthesis.

Lysosomes

Lysosomes are membranous sacs found in eukaryotic cells with enzymes involved in digestion and recycling of cell components.

Golgi Apparatus

The Golgi apparatus is a membranous structure involved in processing and secretion of certain molecules.

Vacuoles

Vacuoles, membranous organelles, can store waste products or materials required by the cell.

Carbohydrates

Carbohydrates are organic compounds made from carbon, hydrogen, and oxygen.
They serve as a primary source of biological energy.
Monosaccharides, disaccharides, oligosaccharides and polysaccharides are the different classes of carbohydrates.

Proteins

Proteins are essential molecules in cells and are composed of amino acids linked together by peptide bonds.
They have diverse functions, including catalysis (enzymes), transport, structural support, and defense.
Amino acids are classified into hydrophobic, hydrophilic, charged-acidic and charged-basic.

Nucleic Acids

Nucleic acids (DNA and RNA) are complex organic molecules containing genetic information.
They are polymers of nucleotides.
DNA is the main genetic material of cells.
RNA plays vital roles in protein synthesis and gene regulation.

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Description

Test your knowledge of cell biology with questions focusing on various cellular components and their functions, including the thylakoid membrane, ribosomes, and lysosomes. This quiz covers key concepts related to plant cell structure, carbohydrate chemistry, and the roles of different organelles.