DNA and CHROMOSOMES - A-level Biology DNA and CHROMOSOMES in eukaryotic and prokaryotic cells

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Learn what a gene, allele and chromosome are. Learn how DNA is stored in chromosomes in eukaryotic cells and what a histone protein and nucleosome are. Compare DNA in eukaryotic and prokaryotic cells. This is from the start of topic 4 AQA A-level Biology.
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5 авг 2024

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Комментарии : 41

@NeawonDerrickGbeadah-wx4xd 10 месяцев назад

Your classes are so helpful to me thanks.

@MissEstruchBiology 10 месяцев назад

You're so welcome

@tayyabanawaz3479 Год назад

Hey, is the change in allele because of a change in the sequence of amino acid (same amino acid but in a different sequence) or that the triplet ( 3 bases) of one amino acid is different that gives a different sequence. Am so confused sorry.

@ifejohnson6593 3 года назад

Your videos are so helpful!!!

@MissEstruchBiology 3 года назад

Really glad you are liking them 😊

@areebahaque5916 2 месяца назад

Miss I have a request can u also make videos for Edexcel AS Biology Unit (1,2,3).Your vdos are the best ❤

@akuawinnie8234 2 года назад

Hi thanks so much - you're videos are the only reason im getting through biology. I'm, not sure if this is a straightforward question or not but since homologous chromosomes are chromosomes with exactly the same genes meaning in fertilisation homologous pairs form, do all humans have exactly the same genes and just different alleles?

@MissEstruchBiology 2 года назад

yes exactly! We all have the same genes, but different versions (alleles)

@arjunamavasya1902 4 года назад

light work

@MissEstruchBiology 4 года назад

Hope it helped

@amyrahadeleye7277 Год назад

Hi Miss Estruch, does the Histone also stop the DNA from being tangled or is its only purpose to help form chromosomes and can you also say the DNA is tightly coiled or do you have to say double helix?

@MissEstruchBiology Год назад

Hello, yes histones help to tightly coil the DNA in a way that makes it fit onto the chromosomes in a nucleus and prevent in tangling

@enourmoussultan2783 2 года назад

Hello miss, thanks for your help, just wanted to ask, in the oxford biology aqa book, it says that prokaryotic cells dont have chromsomes(when talking about the difference of DNA in eukaryotic cells and prokaryotic cells)?

@MissEstruchBiology 2 года назад

Hello, Perhaps it says that as the chromosomes aren't anything like eukaryotic chromosomes. They aren't linear with histones, they are single and circular.

@enourmoussultan2783 2 года назад

@@MissEstruchBiology Oh, ok, miss, even Im quite confused as other places online, it says similar to what you explain. Or maybe, its just im understanding what it says in the book wrong? This is what it says in the oxford aqa biology a level book, section 8.2, pg 205 'In prokaryotic cells, such as bacteria, the DNA molecules are shorter, form a circle and arc not associated with protein molecules. Prokaryotic cells therefore do not have chromosomes. '

@user-my7te8ot8l 4 месяца назад

So before interphase normal body cells have 23 single chromosomes and after interphase there are 46 which are paired?

@lakavimanasasuthan3719 4 года назад

Hi Miss Estruch, What does Functional DNA do? How is it different to mRNA, tRNA and rRNA? Thank you!

@MissEstruchBiology 4 года назад

Functional DNA means that is will code of mRNA and thus a polypeptide chain.. tRNA is the amino acid carrier. rRNA is one of the components which makes up a ribosome.

@lakavimanasasuthan3719 4 года назад

Miss Estruch Thank you, it makes sense now!

@uwotm8770 3 года назад

hi miss, do chromosomes become visible during replication (interphase) or prophase? thanks for the video

@MissEstruchBiology 3 года назад

hello, in prophase 😊

@ia8090 3 года назад

hi miss eustruch! is the single chromosome also called chromatin. and can the chromosomes be also non-homologous because the single chromosome is missing a half?

@MissEstruchBiology 3 года назад

Hello, Chromatin condenses to form the chromosome. Chromatin is the DNA and histone proteins tightly coiled, but this further coils to form the chromosome. Non-homologous chromosomes refers to pairs of chromosomes (that are not attached to each other) that contain the same genes. I think you are describing the fact that one chromosome can appear as a single line or as an X shape made up of two sister chromatids after DNA replication. Hope that helps :)

@ia8090 3 года назад

@@MissEstruchBiology yes that makes sense. thank you:)

@umuvudukotv 9 месяцев назад

I want soft notes on this topic.

@Qeweeeeee 2 года назад

Could u explain how u would have an identical gene but a different version. So different bases or smth

@MissEstruchBiology 2 года назад

Yeah exactly that, the DNA base sequences would be slightly different

@Qeweeeeee 2 года назад

@@MissEstruchBiology oh so wud it have different bases, but code for the same amino acids or code for different amino acids?

@sebby1654 10 месяцев назад

in prokaryotes, you said dna is stored in chromosones and is circular, how can dna be circular and be stored in chromosones, i thought chromosones r linear dna consisting uhh sorry i dont get it

@0x1_chips 3 года назад

Isn’t DNA stored as chromatin in the nucleus and then it condenses to chromosomes before replication?

@MissEstruchBiology 3 года назад

Hello, Chromatin is the term for the DNA wrapped around the histone proteins, which yes, coils and condenses to form a chromosome. The chromosomes themselves condense and become visible in prophase of the cell cycle. Hope that helps 😊

@0x1_chips 3 года назад

@@MissEstruchBiology thankyou! That makes sense. So would it be fine if I said dna is stored as chromatin in the nucleus or do I have to say dna is stored as chromosomes?

@MissEstruchBiology 3 года назад

for AQA you would have to say stored as chromosomes

@0x1_chips 3 года назад

@@MissEstruchBiology ok thank you!

@naomipeller7958 5 месяцев назад

the same genes are found at one locus for homologous chromosomes - is this the same with all humans? will all humans have the same gene at the same locus or does it differ between humans?

@MissEstruchBiology 5 месяцев назад

The locus of a gene is the same for all humans.