The Fundamental Unit of Life

Flashcards based on lecture notes about cells, microscopes, cell organization, and cell components.

What is a cell?

The basic unit of structure and function in living organisms.

What is cytology?

The branch of biology dealing with the study of structure and function of plant and animal cells.

Who is Robert Hooke?

Observed a thin slice of cork (dead cell) under the microscope and saw honeycomb-like structures which he called cells in 1665.

What is a microscope?

An optical instrument that can be used to observe small objects, even cells.

What is the typical size range of cells?

From 10 to 100 microns, although some are visible to the naked eye.

What is an example of a cell having the largest volume in the animal cell?

Ostrich egg.

What is the smallest cell?

PPLO (pleuropneumonia like organism).

What are the three common major functional regions of all cells?

Plasma membrane (or cell membrane), cytoplasm, and nucleus.

What is the plasma membrane made of?

Proteins and phospholipids.

Who proposed the fluid mosaic model of the plasma membrane?

Given by Singer and Nicolson in 1972.

What is passive transport?

A type of membrane transport that does not require energy to move substances across the cell membrane.

What is diffusion?

Movement of substances from their higher concentration to their lower concentration.

What is osmosis?

Water molecules move from their higher concentration to their lower concentration through a semipermeable membrane.

What is active transport?

The movement of any substance through the cell membrane that requires energy, provided by ATP.

Where is the cell wall found?

Plants, fungi, bacterial cells, and certain protists.

What is the plant cell wall made of?

Cellulose.

What are the layers of cell wall?

Middle lamella, primary wall, and secondary wall.

Who discovered the nucleus?

Robert Brown (1831).

What is the nuclear envelope?

A double membranous structure that surrounds the nucleus and separates it from the cytoplasm.

What does the nucleoplasm contain?

Contains nucleoproteins, nucleotides, and a number of enzymes.

What is chromatin?

Hereditary DNA-Protein complex that occurs in the form of fine overlapping and coiled fibers.

What are prokaryotes?

Lack a nuclear membrane and the genetic material lies freely in the form of a nucleoid.

What are eukaryotes?

Have a well-organized nucleus with a nuclear membrane.

What are the functions of the nucleus?

Contains all the genetic information required for growth, development, reproduction, metabolism, and behaviour.

What are Nucleic Acids?

Long chain macromolecules of Deoxyribo Nucleic Acid (DNA) and Ribo Nucleic Acid (RNA).

What are nucleotides?

Basic units of nucleic acids; a condensation product of a pentose sugar, phosphoric acid, and a nitrogen base.

What are purines?

Adenine (A) and Guanine (G).

What are pyrimidines?

Cytosine (C), Thymine (T) and Uracil (U).

What is the structure of DNA?

Consists of two polynucleotide chains which form a double helical staircase.

Who proposed the DNA Model?

Watson & Crick.

What are chromosomes?

Thread-like DNA containing structures located in the nucleus of eukaryotic organisms.

What are chromatids?

A replicated chromosome consists of two identical halves.

What are homologous chromosomes?

Homologous chromosomes are two chromosomes of the same type, size, morphology and arrangement of gene loci (position).

What are genomes?

The complete but single set (n) of chromosomes (all genes) as found in gametes.

How many chromosomes are found in normal human beings body cell?

Each body cell has 46.

What are sex chromosomes?

Those chromosomes which singly or in pair determine the sex of the individual.

What is a gene?

A short segment of DNA.

What is cytoplasm?

The fluid content/protoplasmic mass of the cell inner to the plasma membrane and excluding the nucleus.