Basic Concepts in Biology, Biology tutorial

Introduction:

Biology is a branch of science which mainly deals with the living world. The process of query is similar to such employed in all natural sciences. This is an interesting study which ranges from microscopic cellular molecules to the multi-cellular macro forms of life, about the surface of earth and its living organisms.

Features of Living Things:

Living things can be differentiated from non-living things by a number of features.

i) Movement: All living things can move. Movement implies a change in position which could be from one location to the other).

ii) Nutrition: Living organism wants food to supply the energy and materials for life process. It comprises the net process of taking in and the utilization of foods in animals and also taking in of mineral substances and their consumption in plants.

iii) Respiration: It is the breakdown of food substances taken in by the organism to liberate energy.

iv) Sensitivity: It is the ability of a living organism to get an external stimulus and respond to it.

v) Excretion: It is the elimination of waste products of metabolism from the body of a living organism.

vi) Reproduction: It is the procedure of giving rise to new individuals of the similar type for the continuance of life. Reproduction might be sexual or asexual in nature.

vii) Growth: Living organism can grow. That means increase in size which is generally accompanied by growth. The materials employed for growth are derived from the food taken in by the organism.

viii) Adaptation: It is the possession of traits (structures or functions) which facilitate organisms to live lucratively and to survive in their relevant environments.

FEATURES

PLANT

ANIMALS

Nutrition

Autotrophic nutrition that is, prepares own food by Photosynthesis.

Heterotrophic Nutrition that is, based on plants and other animals for food.

Support

Based on tugor and lignified tissues.

Endoskeleton and Exoskeleton

Movement

Fixed on one spot.

The entire animal can move about fast.

Growth

Might grow big with branching body. Growth is mostly at meristems, is vague.

Body is solid, growth stops at adulthood in higher animals.

Sensitivity

Responds gradually to stimulus by means of hormones.

Sensory system lets rapid reactions.

Cell Structure

Cellulose cell wall & vacuoles having cell sap are present, might have Chloroplasts.

Cell wall is absent. Vacuole and chloroplast are not present.

Plant Cell:

Plant cells are mainly eukaryotic cells, or cells having a membrane bound nucleus. Dissimilar to prokaryotic cells, the DNA in a plant cell is abode in the nucleus. Moreover, to having a nucleus, plant cells as well have other membrane-bound organelles, or tiny cellular structures, which carry out specific functions essential for normal cellular operation. Organelles encompass a broad range of responsibilities which comprise everything from generating hormones and enzymes to giving energy for a plant cell.

Plant Cell - Structures and Organelles

The structures and organelles which can be found in usual plant cells are:

a) Cell (Plasma) Membrane: It is a thin, semi-permeable membrane which surrounds the cytoplasm of a cell, including its contents.

b) Cell Wall: It is the outer covering of the cell which protects the plant cell and provides it shape.

c) Chloroplast: The sites of photosynthesis in a plant cell. They have chlorophyll, a green pigment which absorbs energy from the sunlight.

d) Cytoplasm: It is a gel-like substance in the cell membrane having water, enzymes, salts, organelles and different organic molecules.

e) Cytoskeleton: It is a network of fibers all through the cytoplasm which assists the cell maintains its shape and provides support to the cell.

f) Endoplasmic Reticulum (ER): It is an extensive network of membranes comprised of both areas with ribosome (rough ER) and areas without ribosome (smooth ER).

e) Golgi Complex: It is mainly responsible for manufacturing, storing and shipping some cellular products.

f) Microtubules: It is a hollow rod which functions primarily to aid support and shape the cell.

e) Mitochondria: This organelle produces energy for the cell.

f) Nucleus: It is a membrane bound structure which consists of the cell's hereditary information.

g) Nucleolus: It is a structure in the nucleus which assists in the synthesis of ribosome.

h) Nucleopore: It is a tiny hole in the nuclear membrane which permits nucleic acids and proteins to move into and out of the nucleus.

i) Peroxisomes: It is a tiny structure bound by a single membrane which contains enzymes which generate hydrogen peroxide as a by-product. Such structures are involved in plant processes like photorespiration.

j) Plasmodesmata: Pores or channels among plant cell walls which let molecules and communication signals to pass among the individual plant cells.

k) Ribosome: Comprising of RNA and proteins, ribosome is mainly responsible for protein assembly.

l) Vacuole: It is a structure in plant cell which gives support and participates in a diversity of cellular functions comprising storage, detoxification, security and growth. Whenever a plant cell matures, it usually includes one big liquid-filled vacuole.

Animal Cells:

Animal cells are mainly eukaryotic cells or cells having a membrane-bound nucleus. Dissimilar to prokaryotic cells, DNA in animal cells is abode in the nucleus. Moreover to have a nucleus, animal cells as well includes other membrane-bound organelles or small cellular structures which carry out particular functions essential for normal cellular operation. Organelles encompass a broad range of responsibilities which comprise the whole thing from generating hormones and enzymes to giving energy for animal cells.

Animal Cells - Organelles and Components

The structures and organelles which can be found in typical animal cells are:

a) Cell (Plasma) Membrane: It is a thin, semi-permeable membrane which surrounds the cytoplasm of a cell, including its contents.

b) Centrioles: Cylindrical structures which arrange the assembly of microtubules throughout cell division.

c) Cytoplasm: It is a gel-like substance in the cell.

d) Endoplasmic Reticulum: Widespread network of membranes composed of both areas with ribosome (rough ER) and areas with no ribosome (smooth ER).

e) Golgi Complex: As well termed as the Golgi apparatus, this structure is mainly responsible for manufacturing, storing and shipping particular cellular products.

f) Lysosomes: It is sacs of enzymes which digest cellular macromolecules like nucleic acids.

g) Microtubules: Hollow rods which function mainly to support and shape the cell.

h) Mitochondria -Cell components which produce energy for the cell and are the sites of the cellular respiration.

i) Nucleus: It is a membrane bound structure which includes the hereditary information of cell.

j) Nucleolus: A structure in the nucleus which assists in the synthesis of ribosome.

k) Nucleopore: Tiny hole in the nuclear membrane which lets nucleic acids and proteins to move into and out of the nucleus.

l) Ribosome: Comprising of RNA and proteins, ribosome is mainly responsible for protein assembly.

Difference between plant and animal cell:

Plant cells differ from animal cells in plentiful ways. Such differences are as described below:

Plant Cell:

a) The plant cell comprises an outer rigid cell wall which is build up of cellulose.

b) Plant cell consists of a dissimilar, definite shape since of the firm cell wall. So, the shape of cell is lasting.

c) Plant cell comprises plastids. Most considerable of such is the green chloroplast.

d) The Vacuoles are extremely low and bigger.

e) Centrosome is existed merely in the cells of some plants.

f) Dictyosome is dispersed throughout the cytoplasm. It comprises of stacks of solitary membranous lamellar discs.

g) Lysosomes are only found in the eukaryotic plant cells.

h) Plant cells are bigger as compare to animal cell.

i) Generally the starch is a storage material.

j) All through cytoplasmic division a cell plate which is made up in the centre of the cell.

Animal Cell:

a) In animals, Cell wall is not present. The plasma membrane is the outer-most wrapper.

b) The shape of animal cell is not so exact. This can vary its shape.

c) Plastids are absent.

d) Vacuoles are either not present or extremely small in size and number.

e) All animal cells include centrosomes.

f) Golgi complex is structured in the cytoplasm. It appears as shallow saucer shaped body or narrow neck bowl-like shape. This includes interconnecting tubules in the distal region.

g) Mainly found in each and every cell.

h) Animal cell is extremely small in size.

i) In animals, Glycogen is a storage material.

j) All through cytoplasmic division a furrow appears from the edge to the centre of cell.

Cell Division:

The entire living organism in multicellular organism is composed of cells, that is, the number of cells rises greatly as the organism grows. As new cells build up from pre-existing ones, some means should exist for an individual cell to form more cells. This procedure is termed as cell division. Cell division comprises two distinct methods.

These are meiosis and mitosis.

Meiosis: It is the method of cell division that leads to the production of reproductive cells (or gametes) having partly the chromosome number of the parent cell. Cell made up by meiosis generates gametes and the diploid number of chromosomes is restored throughout fertilization. Meiosis includes two successive cell divisions, first meiotic division, if the parent splits into two, and second meiotic division if the products divide again, giving a sum of four daughter cells. The method is divided into a sequence of stages; Prophase I and II, Metaphase I and II, Anaphase I and II, and Telophase I and II.

Mitosis: It is the ordered method by which the cell nucleus and cytoplasm divide into two each encompassing a nucleus having the similar number and type of chromosomes as the parent cell. The method is divided into four successive stages:  Prophase, Metaphase, Anaphase and Telophase.

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