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Genetics 101 Part 1: What are genes? : Find out about the basics of cells, chromosomes, and the genes contained in your DNA.
相關課程
- Your body is made up of 50 trillion cells,
- cells come in many different varieties,
- with different functions,
- but inside, almost of every cell is a nucleus,
- containing 99.9% of your genes,
- and mitochondria, containing a few more genes.
- All told, you've nearly 20,000 genes,
- your genes are small parts of a long molecule, called DNA,
- or deoxyribonucleic acid.
- If you lined up all the DNA containing all of your genes,
- it would measure 6 feet long,
- but it's coiled, so tightly that it fits in just one cell nucleus.
- DNA is a double stranded molecule composed of sugar,
- phosphate, and four different bases,
- adenine, thymine, cytosine, and guanine.
- These bases spell out the language known as the genetic code.
- The number and order of these four bases determine
- for example, whether you're a chimp, a cow, a banana,
- or a human.
- Most genes are recipes for making specific proteins,
- these recipes are passed down from parents to children,
- from generation to generation.
- When someone says "You have your father's hair.",
- what they mean is "You appear to have inherited a gene
- or genes from your father that makes a protein
- that instructs your hair follicle cells to
- produce hair that curls like your father's",
- but they usually opt for the shorter version.
- Genes tell a cell how to function
- and what traits to express
- more specifically, gene regulators turn other genes on and off
- in different cells, to control cell function.
- The long molecules of DNA, containing your genes,
- are organized into pieces called chromosomes.
- different species have different numbers of chromosomes.
- Humans usually have 46 chromosomes,
- two sets of 23, or simply 23 pairs of chromosomes.
- Chimpanzees have two sets of 24, or 24 pairs of chromosomes.
- Rhesus monkeys have 21 pairs of chromosomes.
- Cows have 30 pairs of chromosomes.
- Chickens have 39 pairs.
- Fruit flies have 4 pairs,
- and bananas have 11 pairs.
- So, what percentage of the DNA in your chromosomes
- do you share with other species?
- You shared 93% of your DNA with Rhesus monkey,
- and 98.5% with our friend, chimpanzee.
- How about with other humans?
- 99.5%
- So, what makes us different, from one another?
- Well, for one thing, SNiPs.
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