Introduction to Cells

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Questions and Answers

What is the primary function of the rough endoplasmic reticulum (ER)?

DNA replication

Energy production

Lipid synthesis

Protein synthesis (correct)

What sequence directs proteins to the endoplasmic reticulum (ER)?

N-terminal signal sequence (correct)

Transmembrane sequence

Internal signal sequence

C-terminal signal sequence

What is the primary role of the Golgi apparatus?

Production of ATP

Molecular warehouse and shipping (correct)

Intracellular digestion

DNA synthesis

What structural unit is a key feature of the Golgi apparatus?

Golgi saccule Signup and view all the answers

What happens if the Golgi apparatus mismanages shipping proteins?

Certain cell functions may cease Signup and view all the answers

What is one of the consequences of defects in Golgi function?

Cystic fibrosis Signup and view all the answers

What type of vesicles are formed by the Golgi apparatus for protein transport?

Secretory vesicles Signup and view all the answers

Which of the following best describes lysosomes?

Intracellular digestion compartments Signup and view all the answers

What is a key difference between proteins destined for the cytosol and those for the ER?

ER proteins have an N-terminal signal sequence Signup and view all the answers

What does the Golgi apparatus do as products move from the cis-face to the trans-face?

Packages and modifies products Signup and view all the answers

What is the smallest structural and functional unit of organisms?

Cell Signup and view all the answers

What is the primary function of DNA in a cell?

To direct the functioning of the cell Signup and view all the answers

Which type of cell has a true membrane-bound nucleus?

Eukaryotic cell Signup and view all the answers

What is cytoplasm primarily composed of?

Cytosol and organelles Signup and view all the answers

Which of the following is NOT a characteristic of cells?

Composed only of proteins Signup and view all the answers

What does cell fractionation help to isolate?

Cell components Signup and view all the answers

Which term refers to the area inside of a cell?

Intracellular Signup and view all the answers

Which of the following is a structure found in eukaryotic cells?

Large ribosomes Signup and view all the answers

What technique is used to isolate organelles from cells?

Cell fractionation Signup and view all the answers

What is the phospholipid bilayer primarily responsible for?

Regulating the movement of substances in and out of the cell Signup and view all the answers

Prokaryotic cells are characterized by having:

No membrane-bound organelles Signup and view all the answers

What is the method of reproduction for prokaryotic cells?

Binary fission Signup and view all the answers

What model describes the structure of the cell membrane?

Fluid mosaic model Signup and view all the answers

Which of the following organelles is considered the control center of the cell?

Nucleus Signup and view all the answers

What type of tails do phospholipids possess?

Hydrophobic tails Signup and view all the answers

Eukaryotic cells can be classified as:

Unicellular or multicellular Signup and view all the answers

Which component does the cell membrane NOT contain?

Nucleic acids Signup and view all the answers

What is the immediate result of differential centrifugation?

Formation of pellets containing cell components Signup and view all the answers

Which statement about the fluid mosaic model is true?

The bilayer allows for fluid movement of components. Signup and view all the answers

What is a common initial symptom of mitochondrial diseases affecting skeletal muscles?

Drooping of the upper eyelid Signup and view all the answers

What is a key function of peroxisomes in the liver?

Detoxifying alcohol Signup and view all the answers

Which enzyme is found in peroxisomes to convert H2O2 to water?

Catalase Signup and view all the answers

What is the most common peroxisomal disorder?

Adrenoleukodystrophy Signup and view all the answers

What happens to fatty acids in individuals with defective peroxisomal proteins?

They accumulate and destroy myelin sheaths Signup and view all the answers

What shape are peroxisomes typically described as?

Oval or spherical Signup and view all the answers

What is the primary function of lysosomal enzymes?

Digestion of large molecules Signup and view all the answers

What process describes the digestion of food particles by lysosomes?

Phagocytosis Signup and view all the answers

What component of the lysosomal membrane ensures the safety of its contents?

Impermeability Signup and view all the answers

What happens to the products resulting from lysosomal digestion?

They are released and reutilized. Signup and view all the answers

Which substance accumulates in residual bodies within non-dividing cells?

Lipofuscin Signup and view all the answers

How does autophagy contribute to lysosomal function?

It recycles damaged cellular components. Signup and view all the answers

What characterizes the enzyme content within lysosomes?

It varies based on tissue metabolic activity. Signup and view all the answers

Which of the following is NOT a function of lysosomes?

Synthesis of proteins Signup and view all the answers

What mechanism is used by cells to remove indigestible materials stored in lysosomes?

Exocytosis Signup and view all the answers

Which characteristic of lysosomes allows them to keep their contents isolated from the rest of the cell?

Impermeable membrane Signup and view all the answers

Study Notes

Cell Theory

The smallest structural and functional unit of organisms is the cell.
All organisms are composed of cells.
Cells arise only from preexisting cells through cell division.

Characteristics of a Cell

Capable of information storage, energy production and utilization.
Exhibits movement and can respond to environmental changes.
Can duplicate for growth, repair, reproduction, and development.
Maintains homeostasis and builds essential molecules like proteins, carbohydrates, and nucleic acids.

Types of Cells

Prokaryotic cells are single-celled organisms, like bacteria.
Eukaryotic cells include more complex structures such as animal and plant cells.

Prokaryotic vs. Eukaryotic Cells

Prokaryotic cells are generally less than 10 µm in size, while eukaryotic cells range from 10-100 µm.
Prokaryotics lack a true membrane-bound nucleus, while eukaryotics have one.
Prokaryotes have circular DNA without proteins; eukaryotes possess linear DNA with associated proteins.
Ribosomes in prokaryotes are smaller than those in eukaryotes.
Prokaryotes are exclusively unicellular; eukaryotes can be unicellular or multicellular.
Reproduction in prokaryotes occurs only through binary fission, whereas eukaryotes reproduce both sexually (mitosis and meiosis) and asexually.

Three Important Cell Regions

Cell Membrane: Outermost boundary; regulates entry and exit of substances.
Nucleus: Control center containing DNA that directs cell functions.
Cytoplasm: Area between the membrane and nucleus with organelles suspended in cytosol.

Cell Fractionation

Technique used to isolate cell components based on size and density.
Involves homogenizing cells and using differential centrifugation to separate organelles.
Biochemical and microscopic techniques are then employed to analyze organelles.

Cell Membrane Structure

Composed of a phospholipid bilayer consisting of hydrophilic phosphate heads and hydrophobic fatty acid tails.
Contains proteins, sterols, and sugars assisting in various functions.
Described by the fluid mosaic model, emphasizing its dynamic nature.

Endoplasmic Reticulum (ER)

Functions as a site for protein synthesis and intracellular storage.
Directs proteins to the appropriate organelles and transports them to the Golgi apparatus.
Signal sequences help in delivering proteins to specific locations.

Golgi Apparatus

Consists of flattened vesicles known as Golgi saccules that modify, sort, and package proteins.
It has distinct regions (Cis-face for receiving, Trans-face for shipping).
Functions as a molecular warehouse and finishing factory for products from the ER, preventing disruptions in cellular functions.

Lysosomes

Membrane-bound vesicles that facilitate intracellular digestion.
Contain lytic enzymes to recycle cellular resources and digest large molecules.
Involved in autophagy, breaking down damaged organelles.

Peroxisomes

Small organelles that produce/utilize hydrogen peroxide (H2O2).
Enzymes are synthesized in cytoplasm and vary based on cell function.
Detoxify harmful substances and break down fatty acids for energy metabolism.

Disorders of Cell Organelles

Defects in lysosomes can lead to lysosomal storage diseases, while peroxisomal disorders result in severe neurological symptoms.
Conditions like X-linked adrenoleukodystrophy and Zellweger syndrome arise from peroxisomal dysfunctions.

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Description

This quiz covers fundamental concepts in cell biology, including the cell theory and the basic structure of cells. It compares prokaryotic and eukaryotic cells and explains the process of cell fractionation used to isolate cell components. Test your knowledge of cell organelles and their functions.