P1 Structure and Function of Main Cell Components

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Melissa Atkinson          S0168232

Unit 5 – Fundamentals of Anatomy and Physiology

Structure and Function of Main

Cell Components

In this assignment I am going to describe the functions and structures of the plasma membrane itself and membrane bound organelles such as mitochondria, golgi apparatus, endoplasmic reticulum and other membrane bound structures.

The cell membrane is also known as the plasma membrane; it is 7nm wide and separates the cell from its surroundings. It is mainly made up of two layers of phospholipids called the bilayer, which have hydrophilic heads (water loving) and hydrophobic tails (water hating). The plasma membrane is selectively permeable, controlling what substances can enter and leave the cell, allowing some molecules through and not others. Substances can move across the plasma membrane by

diffusion, osmosis or active transport, through                   www.ofeducationcommission.com

different proteins embedded in the membrane such as channel and carrier proteins. There are two types of transport, active transport and passive transport. Passive transport such as diffusion is when molecules move across the membrane with no aid from ATP, from an area of high concentration to an area of low concentration.  ATP is a compound that contains a large amount of energy, releasing energy when it is required and is released by the mitochondria. Active transport is when molecules move from an area of low concentration to an area of high concentration, against their concentration gradient with the aid of energy in the form of ATP.

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The nucleus is the largest organelle in the cell; all cells have a nucleus except for red blood cells. It’s surrounded by a double membrane and within that membrane are nuclear pores, which allow for the exchange of substances between the nucleus and the cytoplasm. The nucleus contains chromatin and a structure called the nucleolus. Chromatin is made from proteins and DNA, DNA controls the cells activities and the nucleolus makes ribosomes.

The mitochondria are oval-shaped and are about 1μm wide and up to 7μm long. It has a double membrane which creates compartments within the organelle, each ...

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