DNA, CHROMOSOMES, GENES & ALLELES. GCSE Science Biology

Описание: http://www.sciencetutorial4u.com This video covers DNA and chromosomes for students studying for GCSE Science Biology.

Refer to these timings to cover:

1. From nucleus to DNA 0:30
2. Structure of DNA 1:42
3. What is a gene? 2:28
4. What is an allele? 3:24
5. 46 Chromosomes 3:49
6. Animals have different
number of chromosomes 5:49

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   • DNA, CHROMOSOMES, GENES & ALLELES. GCSE Sc...  

1. From nucleus to DNA 0:30
If you zoom into the nucleus, you will observe a compact structure called a chromosomes and a smaller section of chromosome will lead to genes. Further zooming into gene will lead to DNA which stand for deoxyribonucleic acid.

2. Structure of DNA 1:42
DNA contains information of inheritance. This is achieved by having different base sequence. The DNA is said to have double helix or it can be described as a twisted ladder.

3. What is a gene? 2:28
Genes provide specific characteristics such as eye colour, skin colour and height. Genes can be described as a group of DNA or it can be also described as a small section of chromosome.

4. What is an allele? 3:24
Alleles are different version of the same gene.

5. 46 Chromosomes 3:49
The human body cells contain 46 chromosomes, or it can be called as 23 pairs of chromosome. Gametes which are sex cells ( sperm and egg ) contain half the number of body cells which is 23 chromosomes only. Girls have XX chromosomes and boys have XY chromosomes.

6. Animals have different number of chromosomes 5:49
Different species have different number of chromosomes. For example, cats contain 39 chromosomes which means their gametes will have 19 chromosomes in their cells. To find the number of chromosomes in gametes, you just have to dive it by 2 or just half it.

MUSICS:
"Son of a Rocket" Kevin MacLeod (incompetech.com)
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"Cut and Run" Kevin MacLeod (incompetech.com)
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