Human Cell Structure And Function Pdf

human cell structure and function pdf

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I remember being in Mr. His room looked like the typical high school lab—high, hard tables with Bunsen burners and gas jets that no one was allowed to touch, and a cabinet full of dead things suspended in fluid in jars. My favorite thing about the room was the giant poster of the Triangulum Galaxy I was, am, and always will be irrevocably fascinated by outer space on the wall behind his desk.

GK Questions & Answers Cell its Structure and Functions

Humans are made up of trillions of cells — the basic unit of life on earth. In this article, we explain some of the structures found in cells and describe a few of the many types of cell found in our bodies.

Cells can be thought of as tiny packages that contain minute factories, warehouses, transport systems, and power plants. They function on their own, creating their own energy and self-replicating — the cell is the smallest unit of life that can replicate. However, cells also communicate with each other and connect to create a solid, well stuck-together animal. Cells build tissues, which form organs; and organs work together to keep the organism alive.

Robert Hook first discovered cells in Different cell types can look wildly different, and carry out very different roles within the body. For instance, a sperm cell resembles a tadpole, a female egg cell is spherical, and nerve cells are essentially thin tubes. Despite their differences, they often share certain structures; these are referred to as organelles mini-organs. Below are some of the most important:.

There is normally one nucleus per cell, but this is not always the case, skeletal muscle cells, for instance, have two. The nucleus sends out messages to tell the cell to grow, divide, or die. The nucleus is separated from the rest of the cell by a membrane called the nuclear envelope; nuclear pores within the membrane allow through small molecules and ions, while larger molecules need transport proteins to help them through.

To ensure each cell remains separate from its neighbor, it is enveloped in a special membrane known as the plasma membrane. This membrane is predominantly made of phospholipids, which prevent water-based substances from entering the cell. The plasma membrane contains a range of receptors, which carry out a number of tasks, including being:. The cytoplasm is the interior of the cell that surrounds the nucleus and is around 80 percent water; it includes the organelles and a jelly-like fluid called the cytosol.

Many of the important reactions that take place in the cell occur in the cytoplasm. Both lysosomes and peroxisomes are essentially bags of enzymes. Lysosomes contain enzymes that break down large molecules, including old parts of the cells and foreign material.

Peroxisomes contain enzymes that destroy toxic materials, including peroxide. The cytoskeleton can be considered the scaffolding of the cell. It helps it maintain the correct shape. However, unlike regular scaffolding, the cytoskeleton is flexible; it plays a role in cell division and cell motility — the ability of some cells to move, such as sperm cells, for instance.

The cytoskeleton also helps in cell signaling through its involvement in the uptake of material from outside the cell endocytosis and is involved in moving materials around within the cell. The endoplasmic reticulum ER processes molecules within the cell and helps transport them to their final destinations. In particular, it synthesizes, folds, modifies, and transports proteins. The ER is made up of elongated sacs, called cisternae, held together by the cytoskeleton.

There are two types: rough ER and smooth ER. Once molecules have been processed by the ER, they travel to the Golgi apparatus. The Golgi apparatus is sometimes considered the post office of the cell, where items are packaged and labeled. Once materials leave, they may be used within the cell or taken outside of the cell for use elsewhere.

Often referred to as the powerhouse of the cell, mitochondria help turn energy from the food that we eat into energy that the cell can use — adenosine triphosphate ATP. However, mitochondria have a number of other jobs, including calcium storage and a role in cell death apoptosis. Ribosomes read the RNA and translate it into protein by sticking together amino acids in the order defined by the RNA.

Our body is constantly replacing cells. Cells need to divide for a number of reasons, including the growth of an organism and to fill gaps left by dead and destroyed cells after an injury, for instance. Mitosis is how most of the cells in the body divide.

Both daughter cells have the same chromosomes as each other and the parent. They are referred to as diploid because they have two complete copies of the chromosomes. Meiosis creates sex cells, such as the male sperm and female egg cells. In meiosis, a small portion of each chromosome breaks off and sticks to another chromosome; this is called genetic recombination.

This means that each of the new cells has a unique set of genetic information. It is this process that allows genetic diversity to occur. When you consider the complexity of the human body, it is no surprise that there are hundreds of different types of cell. Below is a small selection of human cell types:.

Stem cells are cells that are yet to choose what they are going to become. Some differentiate to become a certain cell type, and others divide to produce more stem cells. They are found in both the embryo and some adult tissues, such as bone marrow. Also called myocytes, muscle cells are long, tubular cells. Muscle cells are important for a huge range of functions, including movement, support, and internal functions, such as peristalsis — the movement of food along the gut.

They are motile, meaning that they can move. They achieve this movement by using their tail flagellum , which is packed with energy-giving mitochondria. Sperm cells cannot divide; they only carry one copy of each chromosome haploid , unlike the majority of cells, which carry two copies diploid.

Compared with the sperm cell, the female egg cell is a giant; it is the largest human cell. The egg cell is also haploid so that the DNA from the sperm and egg can combine to create a diploid cell.

Fat cells are also called adipocytes and are the main constituent in adipose tissue. They contain stored fats called triglycerides that can be used as energy when needed.

Once the triglycerides are used up, the fat cells shrink. Adipocytes also produce some hormones. Nerves cells are the communication system of the body. Also called neurons, they consist of two major parts — the cell body and nerve processes. The central body contains the nucleus and other organelles, and the nerve processes axons or dendrites run like long fingers, carrying messages far and wide. Some of these axons can be over 1 meter long.

Cells are as fascinating as they are varied. In one sense they are autonomous cities that function alone, producing their own energy and proteins; in another sense, they are part of the huge network of cells that creates tissues, organs, and us.

This article looks at the structure of the foot — including bones, muscles, ligaments, and tendons — and some of the common conditions that affect it. How long are the small and large intestines? Learn more about the intestines, including their length and how they compare with each other. Shrooms may show up on specific drug tests designed for hallucinogens, but many common drug tests do not test for these compounds.

Learn more. What is a cell? Medically reviewed by Alana Biggers, M. Inside the cell Cell division Types Humans are made up of trillions of cells — the basic unit of life on earth. Inside the cell. A simplified diagram of a human cell. Cell division.

Share on Pinterest Cell division is ongoing for our entire life. Cell Types. Share on Pinterest Sperm are the smallest type of human cell.

In a nutshell. Why do some people believe health misinformation? Could transforming alpha cells into beta cells treat diabetes? Related Coverage. What to know about foot anatomy Medically reviewed by Angela M. How long are the intestines? Medically reviewed by Saurabh Sethi, M.

Anatomy and Physiology: Parts of a Human Cell

Cell , in biology , the basic membrane-bound unit that contains the fundamental molecules of life and of which all living things are composed. A single cell is often a complete organism in itself, such as a bacterium or yeast. Other cells acquire specialized functions as they mature. These cells cooperate with other specialized cells and become the building blocks of large multicellular organisms, such as humans and other animals. Although cells are much larger than atoms , they are still very small. The smallest known cells are a group of tiny bacteria called mycoplasmas ; some of these single-celled organisms are spheres as small as 0.


and humans, are multicellular organisms composed of many specialized cell types with their respective functions Most plant and animal cells are visible only under.


4.1: Cell Structure and Function

The cell from Latin cella , meaning "small room" [1] is the basic structural, functional, and biological unit of all known organisms. A cell is the smallest unit of life. Cells are often called the "building blocks of life". The study of cells is called cell biology , cellular biology, or cytology.

A cell is the smallest living thing in the human organism, and all living structures in the human body are made of cells. There are hundreds of different types of cells in the human body, which vary in shape e. However, all cells have three main parts, the plasma membrane , the cytoplasm and the nucleus. The plasma membrane often called the cell membrane is a thin flexible barrier that separates the inside of the cell from the environment outside the cell and regulates what can pass in and out of the cell. Internally, the cell is divided into the cytoplasm and the nucleus.

In this section the learners now expand their knowledge and learn the various cell structures and related functions. The roles of the organelles within the cells need to be introduced and relate structure and location of organelles to their function. Cells differ in size, shape and structure and therefore carry out specialised functions.

Cell Structure And Function Quiz Answers The actual gap between an axonal ending and the muscle cell is called a Within the axonal endings are many small vesicles containing.

What is a cell?

All living organisms are made up of cells. It is the basic, structural, and functional unit of life. Also, it is known as "Building blocks of life".

Humans are made up of trillions of cells — the basic unit of life on earth. In this article, we explain some of the structures found in cells and describe a few of the many types of cell found in our bodies. Cells can be thought of as tiny packages that contain minute factories, warehouses, transport systems, and power plants. They function on their own, creating their own energy and self-replicating — the cell is the smallest unit of life that can replicate. However, cells also communicate with each other and connect to create a solid, well stuck-together animal. Cells build tissues, which form organs; and organs work together to keep the organism alive. Robert Hook first discovered cells in

Cells are the basic building blocks of all living things. The human body is composed of trillions of cells. They provide structure for the body, take in nutrients from food, convert those nutrients into energy, and carry out specialized functions. Cells have many parts, each with a different function. Some of these parts, called organelles, are specialized structures that perform certain tasks within the cell. Human cells contain the following major parts, listed in alphabetical order:.


The Cell Structure and Function. The cell is the lowest level of structure capable of performing all the activities of life. The first cells were observed and named by.


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Eva B.

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Parts of the Cell.

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Humans are multicellular organisms with various different types of cells that work together to sustain life. Other non-cellular components in the.

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