High School Biology : Cell Structures and Organelles

Study concepts, example questions & explanations for High School Biology

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Example Questions

Example Question #61 : Cell Biology

Translation is a process that creates protein from mRNA. Where does translation occur in a eukaryotic cell?

Possible Answers:

Rough endoplasmic reticulum

Nucleus

Golgi apparatus

Cytosol

Correct answer:

Cytosol

Explanation:

Recall that the central dogma of molecular biology states that the information flow within a cell involves DNA replication, transcription, and translation. DNA replication involves the formation of two identical DNA molecules from a single molecule and transcription involves synthesis of mRNA from DNA. The DNA molecules can’t leave the nucleus, therefore, both of these processes occur in the nucleus

Translation involves the synthesis of proteins from mRNA molecules. The mRNA molecules exit the nucleus after transcription (through nuclear pores) and enter the cytosol. The ribosomes in the cytosol bind to mRNA and facilitate translation; therefore, translation occurs in the cytosol.

Example Question #1 : Understanding Other Cell Structures

What is autophagy?

Possible Answers:

The process by which malfunctioning and worn out parts of the cell are broken down and recycled

The automatic defensive response that a nucleus initiates when the cell is under attack

The process by which all malfunctioning and worn out parts of the cell are immediately discarded by being pushed out of the cell membrane

The process by which a T-lymphocyte learns to recognize "self" antigens

Correct answer:

The process by which malfunctioning and worn out parts of the cell are broken down and recycled

Explanation:

Eukaryotic cells are very resourceful in every way they function. When a cell part becomes worn out or non-functional, these part is broken down and recycled by the cell via lysosomal activation. This process is known as autophagy. The biological monomers produced from the catabolic process can then be used to build new polymers and macromolecules.

Exocytosis is the process by which contents from within the cell are expelled across the membrane. This generally occurs to assist cell signaling, such as the exocytosis of neurotransmitters. Positive selection is the process by which T-lymphocytes are presented by "self" antigens. If the T-cell reacts to the "self" antigen, it is destroyed to prevent autoimmune reactions.

Example Question #1 : Understanding Other Cell Structures

Which of the following sequences represents an accurate order of size, from smallest to largest?

Possible Answers:

Atoms, proteins, ribosomes, viruses, mitochondria, a eukaryotic cell

Atoms, viruses, proteins, ribosomes, mitochondria, and a eukaryotic cell

Proteins, atoms, ribosomes, viruses, mitochondria, a eukaryotic cell

A eukaryotic cell, virus, ribosomes, atoms, mitochondria, and proteins

Correct answer:

Atoms, proteins, ribosomes, viruses, mitochondria, a eukaryotic cell

Explanation:

Atoms are the smallest functional unit of matter and are used to construct complex molecules, such as proteins. A protein is composed of numerous smaller atoms.

Ribosomes are composed of ribosomal RNA (rRNA) and proteins, but are smaller than viruses. Viruses are composed of protein coats that house genetic information coded in nucleic acids.

Mitochondria are membrane-bound organelles within the cell. These structures are smaller than the nucleus, but larger than ribosomes. While viruses must be small enough to enter the nucleus through nuclear pores, mitochondria are too large to travel much within the cell.

Cells are the basic functional unit of life. Prokaryotic cells and viruses are both significantly smaller than eukaryotic cells. Eukaryotic cells are relatively large in order to accommodate the various organelles and process that occur within them.

In order from smallest to largest, the answer is atoms, proteins, ribosomes, viruses, mitochondria, a eukaryotic cell.

Example Question #62 : Cell Biology

Which of the following correctly describes the function of a lysosome? 

Possible Answers:

Modify and package protein products prior to export from the cell

Transport molecules through the cytoplasm

Synthesize lipids

Degrade damaged polypeptides

Facilitate bond formation between different types of molecules

Correct answer:

Degrade damaged polypeptides

Explanation:

Lysosomes are membrane-bound organelles in the cell with a low pH internal environment. This low pH environment enables the activity of certain enzymes that reside in the lysosomes. These enzymes, known as hydrolytic enxymes, break down damaged or inactive proteins.

The incorrect answer choices largely outline processes accomplished by other organelles. The smooth endoplasmic reticulum synthesizes lipids. The Golgi apparatus and rough endoplasmic reticulum are responsible for protein modification and packaging prior to export from the cell; frequently, this will include addition of different monomers, such as a monosaccharide or lipid to adjust the protein's identity or function. Transportation of molecules through the cytoplasm is accomplished by the cytoskeleton and microtubule system. 

Example Question #63 : Cell Biology

Ribosomes are found in which domains of life?

Possible Answers:

All three domains

Eukarya only

Bacteria only

Archaea only

Correct answer:

All three domains

Explanation:

Ribosomes are found in all cell types and in all three domains. Recall the central dogma of biology: DNA  RNA  protein. Thus, all cells synthesize proteins using ribosomes. Also, note that although prokaryotes have ribosomes, ribosomes are never membrane-bound. Thus it still holds true that prokaryotes do not have any membrane-bound organelles. 

Example Question #64 : Cell Biology

How many subunits are in ribosomes?

Possible Answers:

Correct answer:

Explanation:

Ribosomes are composed of protein and ribosomal RNA (rRNA). They are made up of 2 subunits—one small and one large.

Example Question #65 : Cell Biology

In the endoplasmic reticulum, chains of carbohydrates can be added to proteins. What is the name for such resulting molecules?

Possible Answers:

Glycoproteins

Phospholipids

Lumen

mRNA

Correct answer:

Glycoproteins

Explanation:

Glycoproteins are proteins that have been modified by the addition of chains of carbohydrates of varying length. Glycosylation of proteins happens in the endoplasmic reticulum and the Golgi apparatus. Phospholipids are not proteins and are thus not synthesized in the endoplasmic reticulum, rather, they are synthesized in the cytosol. mRNA is the nucleic acid product of transcription, which occurs in the cytosol in eukaryotes, and in the cytosol in prokaryotes. Lumen is the term which means "an opening," e.g., the lumen of a blood vessel is the space where the blood flows, the lumen of the endoplasmic reticulum is the space inside the organelle itself. 

Example Question #11 : Understanding Other Cell Structures

Peroxisomes contain an enzyme that breaks down which substance?

Possible Answers:

Carbohydrates

Hydrogen peroxide

DNA

Proteins

Correct answer:

Hydrogen peroxide

Explanation:

Hydrogen peroxide is an example of a reactive oxygen species, made as a byproduct of metabolism. Peroxisomes use the enzyme catalase to catalyze the following reaction: . Hydrogen peroxide can be toxic to a cell if it builds up, thus converting it to harmless substances like water and oxygen gas is an important metabolic function of peroxisomes. Also, note that the breakdown of fatty acids (beta oxidation) occurs in both peroxisomes and mitochondria. Proteins, carbohydrates, and nucleic acids are broken down by the lysosome.

Example Question #12 : Understanding Other Cell Structures

Why do liver cells have more extensive smooth endoplasmic reticula than most other cells of the body?

Possible Answers:

They make the liver smooth 

They are used to make glycoproteins

They are used to detoxify substances

They are not present in liver cells 

Correct answer:

They are used to detoxify substances

Explanation:

One of the functions of the liver is to detoxify certain substances such as alcohol, lactic acid, and drugs. Since the smooth endoplasmic reticulum plays an important role in detoxification, liver cells contain extensive smooth endoplasmic reticula. The process of forming glycoproteins is carried out by the rough endoplasmic reticulum, and to some extent, the Golgi apparatus.

Example Question #67 : Cell Biology

Which organelle is responsible for collecting, packaging, and distributing proteins from the location where they are synthesized to the location where they are used?

Possible Answers:

Rough endoplasmic reticulum

Golgi apparatus

Lysosome

Smooth endoplasmic reticulum

Correct answer:

Golgi apparatus

Explanation:

The golgi apparatus collects, packages and distributes proteins to the locations where they are used. Proteins are always synthesized on ribosomes, which can either be floating in the cytosol, or on the rough endoplasmic reticulum. The smooth endoplasmic reticulum's functions include synthesis of lipids, and detoxification of substances. Lysosomes contain hydrolytic enzymes which break down macromolecules.

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