DNA Structure and Replication: Crash Course Biology #10
video description
Dna- deoxyribonucleic acid, stretching them end to end they would reach the sun 600 times. They r a 6 billion letter code. Dna is made of small repeating units (polymers) called nucleotides. Link them together and u have a polynucleotide. A nucleotide is made of-
- A five carbon sugar molecule called deoxyribose
- A phosphate group
- One of 4 nitrogen bases- adenine, thymine go together and cytosine and guanine go together. G and C pairing is stronger
Structure of dna is double helix(a twisted ladder) its main support is the sugar and phosphate binding together to form 2 twin backbones. These run in opposite directions, O2 pointing up and O2 pointing down. The left hand chain is from 5 prime to 3 prime and the opposite on the right hand chain.
Rna- has only 1 sugar phosphate backbone
- so it is a single stranded molecule, sugar is ribose (one O2 more)not deoxyribose
- Has uracil instead of thymine
Replication- copying of cells, helicase is an enzyme that unwinds the hydrogen bonds of the nitrogen bases, the point where the splitting starts is the replication fork. Top strand- leading strand and bottom strand called lagging strand. These go in opposite directions such that making dna from leading strand is easier than for lagging strand.
Leading strand- rna polymerase, an enzyme adds matching nitrogen bases. Rna primase provides a primase which helps the enzyme to make a new dna strand.
Lagging strand- rna polymerase can only copy dna in 5 prime to 3 prime direction so the copying is done in segments and using many other dna polymerase eg dna ligase
Date: 2022-04-04
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Comments and reviews: 7
Dragonaut111
It's crazy the amount of things your body autonomically controls, I can see sometimes why more ignorant people would think we are created by a higher being. The intrinsic intelligence inside every cell, something that isn't even sentient can create something that we as humans have still not mastered.
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It's crazy the amount of things your body autonomically controls, I can see sometimes why more ignorant people would think we are created by a higher being. The intrinsic intelligence inside every cell, something that isn't even sentient can create something that we as humans have still not mastered.
reply
Rajvee
I was so happy when I saw Rosalind Franklin being properly talked about in the video. In all my biology books, her name is mentioned only in passing. Glad to see that the video honoured her contributions properly.
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I was so happy when I saw Rosalind Franklin being properly talked about in the video. In all my biology books, her name is mentioned only in passing. Glad to see that the video honoured her contributions properly.
reply
Marin
Im fairly certain that the DNA strands run in the 5' to 3' direction. Not the other way around. Then again I am watching this video to understand it better so who knows.
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Im fairly certain that the DNA strands run in the 5' to 3' direction. Not the other way around. Then again I am watching this video to understand it better so who knows.
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Claire
Thank you for the video! There is a mistake at 10: 50-10: 59. In the video it said that the lagging strand runs 3'-->5' but the lagging strand actually runs 5'-->3'.
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Thank you for the video! There is a mistake at 10: 50-10: 59. In the video it said that the lagging strand runs 3'-->5' but the lagging strand actually runs 5'-->3'.
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Hukkum
good luck on the science exam you have on monday, and your only studying cause you failed the maths one you had today, and dont want to repeat that
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good luck on the science exam you have on monday, and your only studying cause you failed the maths one you had today, and dont want to repeat that
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Ellice
When he-s actually just holding a short stubby string and talking to it, then actually adding the dna strand when editing the vid --
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When he-s actually just holding a short stubby string and talking to it, then actually adding the dna strand when editing the vid --
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Arman
Everyone-s here commenting how they always watch Crash Course to cram for a test. Then there-s me, just watching these for fun -
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Everyone-s here commenting how they always watch Crash Course to cram for a test. Then there-s me, just watching these for fun -
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