What is DNA?

DNA is the hereditary material in humans and almost all other organisms. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).
The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). Human DNA consists of about 3 billion bases, and more than 99 percent of those bases are the same in all people. The order, or sequence, of these bases determines the information available for building and maintaining an organism, similar to the way in which letters of the alphabet appear in a certain order to form words and sentences.
DNA bases pair up with each other, A with T and C with G, to form units called base pairs. Each base is also attached to a sugar molecule and a phosphate molecule. Together, a base, sugar, and phosphate are called a nucleotide. Nucleotides are arranged in two long strands that form a spiral called a double helix. The structure of the double helix is somewhat like a ladder, with the base pairs forming the ladder’s rungs and the sugar and phosphate molecules forming the vertical sidepieces of the ladder.
An important property of DNA is that it can replicate, or make copies of itself. Each strand of DNA in the double helix can serve as a pattern for duplicating the sequence of bases. This is critical when cells divide because each new cell needs to have an exact copy of the DNA present in the old cell.

VOCABULARY

Mitochondria are structures within cells that convert the energy from food into a form that cells can use.

Nucleotide: A nucleotide is an organic molecule made up of a nucleotide base, a five-carbon sugar (ribose or deoxyribose) and at least one phosphate group. Nucleotides make up the basic units of DNA and RNA molecules.

why do we have day and night?

WHY DO WE HAVE DAY AND NIGHT?

Why do we have day and night? 
We have day and night because the Earth rotates. It spins on its axis, which is an imaginary line passing through the North and South Poles.

How long does it take the Earth to turn around?  
The Earth takes a whole day (24 hours) to make a complete turn.

Why is the Sun in the sky at some times and not at other times? 
At any time half of the Earth faces the sun. This part has day. The other half of the Earth faces away from the Sun. It receives no light. It is dark and has night.

 
Why does the sun seem to move across the sky? 
The Sun does not move. It seems to move across the sky starting in the east in the morning, moving toward the south at noon, and then toward the west as the day ends. It is the Earth turning that makes it seem as though the Sun is moving.

Electricity

ELECTRICITY

Without electricity our lives would be darker and colder.
 Many appliances in our homes use mains electricity to work. We normally get electricity from the mains or batteries.
Small electrical appliances often use batteries which store electricity.( eg. Mobile phones, Mp3). These appliances can be moved place to place.Batteries run down and need to be replaced or recharged.
A complete circuit is when all the components are set up correctly to allow for electricity to flow. Electricity only flows when the circuit is complete with no gaps.
Conductors are materials that can carry electricity.Many materials conduct electricity, metals such as copper, steel, aluminium.

VOCABULARY

 Appliances are any term in your home which uses electricity.(TV, fridges, computers and many others).

BATTERY

Mains allow electricity to reach our homes.

A battery is the component which provides electrical power to a circuit.


A plug goes into a mains to provide power to an appliance. 

PLUG

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