Chromosome, chromatid, chromatin?

Hello,

I'm revising The Cell Cycle for AS Biology and I'm a little confused on the differences between these three words. I was wondering if anyone knew of the definitions or differences, but in reference to a level biology.

Many thanks!
Snowy.

Reply 1

Changing Skies

22

Original post by snowy africa

Hello,

I'm revising The Cell Cycle for AS Biology and I'm a little confused on the differences between these three words. I was wondering if anyone knew of the definitions or differences, but in reference to a level biology.

Many thanks!
Snowy.

Chromosome- a structure that contains both the DNA of an organism as well as the proteins that compose the structure.

Chromatid- these are the identical copies of a chromosome's DNA molecule which are formed by DNA replication.

Chromatin- a complex of nucleic acids and proteins found in the cell nucleus; it condenses during cell division to form a chromosome.

Does that help at all? :smile:

Posted from TSR Mobile

Reply 2

R T

13

Changing skies has given a really good answer :smile:

If you don't like formal definitions, then:

A chromosome is just a long piece of DNA
A chromatid is a copy of a chromosome - there are 2 just before a cell divides.
Chromatin is just what you call chromosomes when they are wrapped up in proteins.

Reply 3

Delta, Δ

7

Original post by Changing Skies

Chromosome- a structure that contains both the DNA of an organism as well as the proteins that compose the structure.

Chromatid- these are the identical copies of a chromosome's DNA molecule which are formed by DNA replication.

Chromatin- a complex of nucleic acids and proteins found in the cell nucleus; it condenses during cell division to form a chromosome.

Does that help at all? :smile:

Posted from TSR Mobile

Hi, isn't a chromatid one half of a chromosome? :smile:

Reply 4

Changing Skies

22

Original post by Delta, Δ

Hi, isn't a chromatid one half of a chromosome? :smile:

Oh god I can't remember :colondollar:

they were just definitions I had from last year in my phone notes, that wasn't off the top of my head :tongue:

Reply 5

R T

13

Original post by Delta, Δ

Hi, isn't a chromatid one half of a chromosome? :smile:

Technically, it would be better to say that a chromatid pair is two copies of 1 chromosome.

Saying something is half of a chromosome implies that it's a single strand of DNA or that it's a chromosome that's been chopped in half - both of which are (usually) nonsense.

Reply 6

Tillybop

18

Original post by snowy africa

Hello,

I'm revising The Cell Cycle for AS Biology and I'm a little confused on the differences between these three words. I was wondering if anyone knew of the definitions or differences, but in reference to a level biology.

Many thanks!
Snowy.

Chromatin is just the normal form of DNA found in the cell when no replication is taken place. The chromosomes only form before mitosis. It's just strands of DNA, with no real arrangement.

Chromosomes are the condensed form of the chromatin. Here proteins bundle the chromatin (DNA) up into the chromosomes so that it is easier to move the DNA to the right place when it is replicated.

A Chromatid is just half of a chromosome - like one strand of it. Two chromatids join to make a single chromosome. That means that the chromosome splits down the middle during replication, with a chromatid going to each side. :smile:

Reply 7

ummm

16

Fun fact: if you were to line up all of the DNA in one of your cells it'd be 2 metres long. We're able to fit all of this into our cells because it's all packaged up, condensing it loads to form chromatin.

If you were to line up all of the DNA in all of your cells, it'd be long enough to go to the sun and back 700 times. :smile:

Reply 8

Hayder120

2

For those of you wanting OCR biology notes for either AS and A2.

Have a look for my post: http://www.thestudentroom.co.uk/showthread.php?t=2632967

your welcome, please if you want to give feedback, complement my teacher, NOT ME.

Chromosome, chromatid, chromatin?

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