Cell Biology Overview

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Questions and Answers

What is the primary reason cells remain small as they grow?

To reduce energy consumption

To enhance their appearance

To fit into small spaces

To maintain a high surface area to volume ratio (correct)

Which structure is NOT common to all cells as per Cell Theory?

Cell wall (correct)

Nucleoid or nucleus

Plasma membrane

Cytoplasm

How do prokaryotic cells reproduce?

Meiosis

Binary fission (correct)

Mitosis

Budding

What limits the size of cells according to the information provided?

Rate of material exchange Signup and view all the answers

Which of the following structures is characteristic of prokaryotic cells?

Ribosomes Signup and view all the answers

What characteristic differentiates archaea from eubacteria?

Cell wall composition Signup and view all the answers

Why is the resolving power of electron microscopes much greater than that of light microscopes?

Electrons have a shorter wavelength than visible light Signup and view all the answers

What is a typical size of cells mentioned in the content?

0.002 cm Signup and view all the answers

What is the primary role of ribosomes in a cell?

Protein synthesis Signup and view all the answers

Which of the following describes the rough endoplasmic reticulum?

It is involved in protein synthesis. Signup and view all the answers

What divides the eukaryotic cell into compartments for different functions?

Endomembrane system Signup and view all the answers

Which component is NOT part of the endomembrane system?

Ribosomes Signup and view all the answers

How many meters long is human DNA that fits into a nucleus?

2 meters Signup and view all the answers

What role does the organizational control mechanism have during embryonic development?

It allows cells to form tissues and anatomical structures. Signup and view all the answers

Why is understanding the cell census particularly important?

It provides a realistic picture of molecular interactions within a cell. Signup and view all the answers

What is the approximate volume of an E.coli cell?

1 fL Signup and view all the answers

What percentage of an E.coli cell's total mass is protein?

30 percent Signup and view all the answers

How many carbon atoms are estimated to be present in an E.coli cell?

10 billion Signup and view all the answers

What is the mean spacing between protein molecules within a typical cell?

10 nm Signup and view all the answers

Which characteristic of E.coli makes it a favorable model organism for experiments?

Its rapid growth rate and easy culturing. Signup and view all the answers

What is the characteristic mass of each amino acid when estimating the number of proteins in a cell?

100 Da Signup and view all the answers

What is the approximate number of proteins in the cytoplasm according to the calculations provided?

2 × 10^10 Signup and view all the answers

Which of the following best describes the size of the macromolecules in the cell?

Similar to the mean spacing between macromolecules Signup and view all the answers

What fraction of the surface area of E. coli is covered with membrane proteins?

1/2 Signup and view all the answers

How is the protein concentration in the cytoplasm expressed?

C prot = 2 × 10^10 / 1μm3 Signup and view all the answers

What is the estimated membrane surface area of E. coli?

6 μm² Signup and view all the answers

What is the relation between the mean spacing of proteins and their size in cells?

Spacing is equal to size Signup and view all the answers

How many lipid molecules are estimated to be present in the E. coli membranes?

4 × 10^7 Signup and view all the answers

What dimensional characteristic of E. coli membranes is primarily discussed?

Bilayer construction Signup and view all the answers

What is one primary function of mitochondria in eukaryotic cells?

Transferring energy from macromolecules to ATP Signup and view all the answers

Which type of vacuole is primarily found in plant cells?

Central vacuole Signup and view all the answers

Which membrane structure is NOT found in mitochondria?

Thylakoid membrane Signup and view all the answers

What type of DNA do mitochondria contain?

Single, circular DNA Signup and view all the answers

What process do mitochondria use to replicate?

Binary fission Signup and view all the answers

Which of the following diseases is associated with malfunctioning mitochondria?

Parkinson’s Signup and view all the answers

What characteristic is NOT true regarding ribosomes found in eukaryotic cells?

They are found only in the plasma membrane. Signup and view all the answers

Which organelle is involved in oxidative metabolism?

Mitochondrion Signup and view all the answers

What theory supports the idea that mitochondria and chloroplasts originated from prokaryotic cells?

Endosymbiosis theory Signup and view all the answers

What is the approximate size of mitochondria?

~1 - 10 microns Signup and view all the answers

Study Notes

Microscopy Resolution

Light microscopes resolve structures 200 nm apart; electron microscopes resolve structures 0.2 nm apart.

Cell Theory Components

All cells share basic structures: genetic material (nucleoid/nucleus), cytoplasm (semifluid matrix), and plasma membrane (phospholipid bilayer).

Cell Size and Function

Cells remain small to maintain efficient metabolism and material exchange with the environment.
Larger cells require more energy and risk a low surface area-to-volume (SA:Vol) ratio, decreasing viability.
High SA:Vol ratio promotes effective nutrient uptake and waste elimination, making cell division essential during growth.

Human Cell Count and Size

Average human contains about 100 trillion cells; composed of roughly 200 different cell types.
Typical cell size is approximately 0.002 cm (20 μm), allowing about 1250 cells per inch.

Prokaryotic Cells Characteristics

Prokaryotic cells lack a membrane-bound nucleus; genetic material is located in the nucleoid.
Types of prokaryotes include archaea (extreme environments) and bacteria (common, eubacteria).

Prokaryotic Bacterial Reproduction

Asexual reproduction occurs mainly through binary fission, where DNA duplicates before the cell divides.

Eukaryotic Cells Key Features

Ribosomes serve as the site for protein synthesis, made from ribosomal RNA and proteins.
The endomembrane system organizes cellular functions through membranes, including:
- Endoplasmic reticulum (ER)
- Golgi apparatus
- Lysosomes

Endoplasmic Reticulum Functions

Rough ER synthesizes proteins (about half of the cell’s proteins) for secretion or for use within lysosomes or the plasma membrane.

Vacuole Types

Vacuoles are versatile membrane-bound structures; types include:
- Central vacuole (plant cells)
- Contractile vacuoles (some protists)
- Storage vacuoles

Mitochondria Overview

Mitochondria are present in all eukaryotic cells, vital for oxidative metabolism and ATP production.
Surrounded by two membranes: a smooth outer membrane and a folded inner membrane (cristae) with an internal matrix.
Contain their own DNA and are implicated in age-related diseases due to dysfunction.

Endosymbiosis Theory

Mitochondria and chloroplasts are believed to have originated through endosymbiosis, suggesting they were once independent prokaryotic organisms.

Cell Census Importance

Understanding individual molecules and their distances within cells provides insight into biological phenomena.
Cells are densely packed, with mean spacing between proteins around 10 nm, highlighting metabolic activity.

E. Coli as a Model Organism

E. coli is easy to isolate and culture in laboratories, significant in research for high growth rates and genome sequencing.
Carry plasmids, enabling manipulation through molecular biology techniques.

E. Coli Cellular Composition

E. coli typically has a volume of 1 fL and a mass near 1 pg; about 30% dry mass is protein.
Estimated protein content is approximately 0.15 pg, indicating high molecular crowding.
Number of proteins calculated to be around 3,000,000 in a single cell.

E. Coli Membrane and Proteins

E. coli has inner and outer membranes with a surface area of about 6 μm², with membrane proteins covering half of this area.
The census of proteins and membranes is crucial for understanding cellular function and mechanisms.

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Description

This quiz covers fundamental concepts in cell biology, including the differences between light and electron microscopes, the Cell Theory, and the reasons for cell size limitations. Test your knowledge on cellular structures and their functions as essential components of life.