Chapter 1: Cells and Genomes

Cell biology

It is the study of the structure, function, and behavior of cells.

Heredity

It is the central definition of life and distinguishes life from other processes.

Unicellular organisms

They are the simplest organisms with a naked nucleus and are devoid of membrane-bound organelles like mitochondria, chloroplasts, etc. Eg: Amoeba, Bacteria, etc

Multicellular organisms

They are organisms with a well-defined nucleus and membrane-bound organelles like mitochondria, chloroplast, etc. Eg: Trees, fungi, humans, etc.

Genome

Totality of its genetic information as embodied in its complete DNA sequence.

Building block of life

DNA (deoxy ribonucleic acid)

Guanine binds with Cytosine

Triple hydrogen bonds

Adenine binds with Thymine

Double hydrogen bonds

Replication

The DNA replicates itself with the help of mainly the DNA-dependent DNA polymerase enzyme.

Transcription

The process of copying the genetic material from one strand of the DNA into RNA is termed transcription.

Translation

It refers to the polymerization of amino acids to form a polypeptide.

Proteins

Catalyst

Genetic code

triplets in nature

Phospholipid bilayer

It is formed of a double layer of lipid molecules sand witched between two layers of protein.

Smallest organism

Bacterium ***Mycoplasma genitalium***

Prokaryotes

Primitive, small, and simple

Eukaryotes

Advanced, and complex

Cocci

spherical

Bacilli

rod-shaped

Spirillum

spiral like

Vibrio

comma shaped

Archaebacteria

They are special and survive in some of the harshest habitats.

Mutations

An error or random accident which occurs during cell divisions.

Horizontal (intercellular) transfer

A piece of DNA can be transferred from the genome of one cell to that of another—even to that of another species. This process is in contrast with the usual vertical transfer of genetic information from parent to progeny.

DNA segment shuffling

two or more existing genes can break and rejoin to make a hybrid gene consisting of DNA segments that originally belonged to separate genes.

Gene duplication

an existing gene can be accidentally duplicated to create a pair of initially identical genes within a single cell; these two genes may then diverge in the course of evolution.

Intragenic mutation

an existing gene can be randomly modified by changes in its DNA sequence, through various types of errors that occur mainly in the process of DNA replication.

Virus

acellular organism