A Tout into the Cell

By: mohammed AlbenSaad

LEARNING OBJECTIVES

CellCytoplasmCytoskeletonCytosolCell nucleusCell NucleolusMitochondria

They contain membrane-bound organelles, such as the nucleus, while prokaryotic cells do not.

Differences in cellular structure:

eukaryotes include the presence of mitochondria, chloroplasts, cell wall and the structure of chromosomal DNA.

Eukaryotic cells:

functions: There are some types of cells are specialized to perform specific functions for example: nerve cells whose function is to transmit tiny electrical pulses around an animal's nervous system.Although different types of cells generally have different specialized functions, some types of processes are common to all, or at least most cell

Robert Hooke who discovered the cells ..

Cytoplasm Cytoplasm is the

substance of a cell other than that of the nucleus.

Cytoplasm is made up of three major elements; cytosol, organelles, and inclusions.

Most cellular activities happen in the cytoplasm. The cytoplasm can be thought of as the “factory area” of the cell.

The structure of the cytoplasm:• contents of cells between the plasma membrane and nucleus envelope.

It consists of a set of organelles suspended in a liquid called essential cytosol, its consists mostly of water containing mineral salts and organic materials dissolved .

The function of the cytoplasm:responsible for many cellular

processes like:-Movement of the different

cellular elements.Convert physical and chemical

stimuli into action potentials.Synthesis and secretion of

steroids.

Cytoskeleton:It is a series of intercellular

protein that help the cell with shape.

The structureThe main structures are:Microfilaments: are hollow tubes made of

tubulin. Intermediate filamentsMicrotubules

The function of cytoskeletonMake the shape of the cell

without need to wallsOrganelle movement: help move

organelles from place to place in the cell.

It is the fluid in which organelles of the cell reside. This is often confused with cytoplasm, which is the space between the nucleus and the plasma membrane. 

Cytosol

The structure of cytosol :It is composed of water, salts and organic molecules. Cytosol is composed of a mixture of cytoskeleton filaments, organic and inorganic molecules that are dissolved. The inner, more fluid and granular potion of the cytoplasm is known as the endoplasm.

The function of cytosol

It has enzymes that take molecules and break them down, so that the individual organelles can use them as they need to. The cytosol also contains the cytoskeleton which gives the cell its shape and can help in the movement of the cell. 

Cell nucleus:It is a membrane-enclosed organelle found in eukaryotic cells and It contains most of the cell's genetic material.

The Structure of Cell nucleus:

1- Nuclear envelope :known as nuclear membrane, consists of two cellular membranes, an inner and an outer membrane, arranged parallel to one another.

2- Nuclear pores: which provide aqueous channels through the envelope, are composed of multiple proteins.

3- Nuclear lamina:two networks of intermediate filaments provide the nucleus with mechanical support.

It is composed mostly of lamin proteins

4- Chromosomes: The cell nucleus contains the majority of the cell's genetic material in the form of multiple linear DNA molecules organized into structures called chromosomes

Each human cell contains roughly two meters of DNA. During most of the cell cycle these are organized in a DNA-protein complex known as chromatin

5- Nucleolus:

It is a discrete densely stained structure found in the nucleus. It is not surrounded by a membrane, and is sometimes called a suborganelle

The main roles of the nucleolus are to synthesize rRNA and assemble ribosomes

The function of nucleus

The nucleus is a highly specialized organelle that serves as the information processing and administrative center of the cell.

It coordinates the cell's activities, which include growth, intermediary metabolism, protein synthesis, and reproduction

Mitochondria

Mitochondria is a membrane bound cellular structure and is found in most of the eukaryotic cells.

Structure of mitochondria:Outer membrane It is smooth and is composed of equal amounts of phospholipids and proteins. It has a large number of special proteins known as the porins. Inner membrane It is folded into a number of folds many times and is known as the cristae. This folding help to increase the surface ares inside the organelle. 

Matrix The matrix of the mitochondria is a complex mixture of proteins and enzymes. These enzymes are important for the synthesis of ATP molecules, mitochondrial ribosomes, tRNAs and mitochondrial DNA.

Functions of mitochondria: The most important function of the

mitochondria is to produce energy. The energy known as ATP molecules.

It is also help in building certain parts of blood and hormones like testosterone and estrogen. 

play important role in the process of apoptosis or programmed cell death.