What is Biology?

Prepared by Ana Carla T. Villarmente

Biology

• “bios” = life• “logus” = study• BIOLOGY = study of life• The study of life

extends from the microscopic scale of the molecules and cells that make up organisms to the global scale of the entire living planet.

Branches of Biology

• Anatomy• Biochemistry• Biotechnology• Botany • Cell Biology/ cytology• Ecology• Entomology• Genetics

• Histology- cells and tissue

• Ichthyology- fish• Microbiology-

microorganisms• Ornithology-birds• Pathology- diseases• Taxonomy- naming and

classification, etc. etc

Characteristics of Living Things

• Order

• Evolutionary adaptation

• Response to the environment

• Regulation

• Energy processing

• Growth and development

• Reproduction

Levels of Biological Organization

Biosphere= all ecosystems

Ecosystem= consists of all organisms living in a particular area, as well as the nonliving, physical components of the environment

Community= consists of various populations of organisms living together in a given area

Population= a group of organisms of the same species in any given area.

Organism= within a population there are organisms, just one of those organisms is called an organism. For example, within a population of lions, there is a lion.

Levels of Biological Organization.p2

Organ system= consists of different organs that work together for a specific function.

Organ= consists of different tissues that function together to do a certain job

Tissue= consists of similar cells that work together

Cell= the smallest unit of life that is able to carry out all the functions of living things

Molecule= consists of different atoms. For example, DNA, within DNA there are oxygen atoms and different proteins.

Atom= the smallest unit of matter that has the chemical properties of a particular element.

Chemical Foundations of Biology

• Organic moleculesa. Carbohydratesb. Protein c. Nucleic acidd. Fats and lipids• Inorganic molecules• Vitamins• Elements• Water

Organic molecules

Inorganic molecules

Parts of the cell

• 3 main parts:1. Plasma membrane

2. Cytoplasm and organelles

3. nucleus

• All cells are protected by a membrane called the cell membrane. Plant cells however also have a cell wall in addition...

• It is the outermost cell surface which separates the cell from the external environment

1. Plasma membrane or cell membrane

Parts of the cell

2. Cytoplasm and organelles

• The functions of animal cell are all carried out by the different cell organelles. These cell organelles function as a unit and regulate the activities of the cell on the whole. The different cell organelles present in an animal cell are

• a. Endoplasmic Reticulum - The endoplasmic reticulum is a network for transportation of certain critical substances in and out of the nucleus. The endoplasmic reticulum is seen like a network of interconnecting pathways to enable the transport of molecules. There are two kinds of ER, namely Rough ER and Smooth ER. Rough ER has ribosome molecules attached to its surface while the smooth ER does not have ribosome molecules attached to its surface.

• c. Lysosomes - Lysosomes are referred to as suicide bags of the cell. They are involved in clearing the unwanted and waste materials from the cell. The lysosomes contain hydrolytic enzymes that are destructive. they kill the toxic materials of the cell time to time. They engulf materials like damaged organelles, virus, bacteria and food particles.

• b. Golgi Apparatus - The Golgi apparatus is involved with processing and packaging of the molecules synthesized by the cell mainly the proteins ready for secretion. The ER transports the proteins in their crude form to the golgi apparatus. The golgi apparatus packages the proteins developing them into primary, secondary and tertiary proteins respectively.

• d. Mitochondria/ mitochondrion - The mitochondria is also referred to as the power house of the cell. It is a double membrane organelle that helps in energy production for the cell. The energy is generated in the form of ATP. Mitochondria also has its own genetic material called the mitochondrial DNA which is circular. The energy is generated from the glucose we take in by a process called the cellular respiration.

e. Ribosomes - The Ribosome is involved in protein synthesis. It consists of two sub units. Protein synthesis primarily occurs in the ribosomes. The ribosomes may be found freely floating in the cytoplasm or may be found attached to the ER.

• g. Vacuole - The vacuole is a large empty storage organelle. They store excess water or food. It is present in many numbers within the cell floating in the cytoplasm. (More discussion in plant cells)

Functions of the Cell

h. Cytoskeleton• An interconnected system

of fibers, threads and interwoven molecules that give structure to the cell

• Main components: microtubules, microfilaments, and intermediate filaments. All are assembled from subunits of protein.

h. Cytoskeleton• An interconnected system

of fibers, threads and interwoven molecules that give stucture to the cell

• i. Centriole• It is a cylinder-like structure

that occurs in pairs• Centrioles function in cell

division

• The cells perform various activities with the aid of the many cell organelles. These cells function together as a unit and form tissue, for example Muscle tissue ( cluster of muscle cells ), A group of similar tissues join together to form an Organ for example stomach, Liver etc. A group of similarly functioning organs group together to form an organ system for example Digestive system, Respiratory system.

• Thus, these cells very tiny and invisible to the naked eye perform all the activities in coordination with the other body cells and help the organism survive.

3. Cell Nucleus

• 1. Cell Nucleus - The nucleus is referred to as the heart of the cell. The nucleus houses the genetic material of the organism which is the DNA. DNA replication and RNA synthesis occurs in the nucleus. It regulates the activities of the other cell organelles thus a very important cell organelle. The cell nucleus is bound by a definite membrane called the nuclear membrane that separates the nucleus from the cytoplasm.

The double helix: DNA or deoxyribonucleic acid make up the chromosomes and are the base of the genetic code.

The discovery of the double elix

• The realization that the structure of DNA is that of a double-helix by which genetic information is stored and copied in living organisms is widely considered one of the most important scientific discoveries of the 20th century..

James D. Watson, Francis Crick, and Maurice Wilkins each received one third of the 1962 Nobel Prize in Physiology or Medicine for their contributions to the discovery

Plant cells are larger than animal cells

• Plant cells can be larger than animal cells • Normal range for an animal cell: from 10 to

30 micrometers • Plant cell: from 10 to 100 micrometers. • Main structural differences between plant and

animal cells: additional structures found in plant cells. These structures include: chloroplasts, the cell wall, and vacuoles.

Chloroplasts

• Plant cells use sunlight as their energy source; the sunlight must be converted into energy inside the cell in a process called photosynthesis. Chloroplasts are the structures that perform this function. They are rather large, double membrane-bound structures (about 5 micrometers across) that contain the substance chlorophyll, which absorbs sunlight. Additional membranes within the chloroplast contain the structures that actually carry out photosynthesis.

(In animal cells, the mitochondria produces the majority of the cells energy from food. It does not have the same function in plant cells).

Vacuoles

• Vacuoles are large, liquid-filled organelles found only in plant cells. Vacuoles can occupy up to 90% of a cell's volume and have a single membrane. Their main function is as a space-filler in the cell, but they can also fill digestive functions similar to lysosomes (which are also present in plant cells). Vacuoles contain a number of enzymes that perform diverse functions, and their interiors can be used as storage for nutrients or, as mentioned, provide a place to degrade unwanted substances.

The Cell Wall

• Another structural difference between in plant cells is the presence of a rigid cell wall surrounding the cell membrane. This wall can range from 0.1 to 10 micrometers thick and is composed of fats and sugars. The tough wall gives added stability and protection to the plant cell.

The Microscope and Microscopy

• Microscope – a tool in Biology

• Microscopy – is a technique in used to examine biological structure, function, and procceses. Uses different types of microscopes, specimen and stains.

• « Discovery in Science is parallel to the invention of tools. »

– Phase and Contrast microscope – is an optical microscopy illumination technique in which small phase shifts in the light passing through a transparent specimen are converted into contrast changes in the image.

• Electron microscope - is a type of microscope that uses a particle beam of electrons to illuminate the specimen and produce a magnified image. There are two types: Scanning Electron microscope (SEM) and Transmission Electron Microscope (TEM).Scanning electron microscope image of an

ant. Its eye is approximately 300 microns wide. (Dartmouth Electron Microscope Facility/Dartmouth College)

The Cell – the basic unit of life

Type of Cell

Size DNA Complexity Example

Eukaryotic Large True Complex Human

Eubacteria Small Circular Simple Bacteria

Archaea Small Circular Simple Thermophilic bacteria

3 domains of Life (Three types) : Eukaryotic, Eubacteria, Archaea

Transport in & out of the cell

Type of transport Passive Active

Driving energy Kinetic ATP

Types Diffusion, Osmosis, Facilitated diffusion,

Electron pump, Co-transport, exocytosis, endocytosis, pinocytosis,

•Two kinds : passive and active