Protein Synthesis and Mitosis/Meiosis

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Where are proteins made?
Proteins are made in the cell by organelles called ribosomes.
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Why are proteins made in the ribosomes?
DNA is needed to make proteins but it found in the cell nucleus and can't move out of it to reach the ribosomes in the cytoplasm as it's really big. This is therefore done using mRNA, which is like a messenger between the two.
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Describe the process of transcription.
The two DNA strands unzip and the DNA is used as a template to make the mRNA. Base pairing ensures it's complementary, so an exact match to the opposite strand.
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Describe the process of translation.
The single strand of mRNA moves out of the nucleus and joins with a ribosome. Amino acids that match the mRNA code are brought to the ribosome by molecules called tRNA. The ribosome then sticks the acids together in a chain to make a protein.
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What is the more scientific name for protein?
When the ribosome sticks the acids together it creates a polypeptide (protein). It follows the order of the triplet of bases (codons) in the mRNA.
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Describe the first process of mitosis
If the cell gets a signal to divide it needs to duplicate it's DNA, so there's one copy for each new cell. The DNA is copied and forms X-shaped chromosomes where each 'arm' of the chromosome is an exact duplicate of the other.
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What happens after the DNA has been copied?
The chromosomes then line up at the centre of the cell and are pulled apart by cell fibres. The two arms of each chromosome go to opposite ends of the cell.
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What forms around these chromosomes at the opposite ends of the cell?
Membranes form around each set of chromosomes which become the nuclei of the two new cells.
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Lastly, what divides and what is produced?
The cytoplasm divides, producing two new diploid cells containing exactly the same DNA.
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Where does mitosis take place and why?
Mitosis takes place all over our bodies as our cells are constantly dividing to produce more cells for growth and repair. This is why they are genetically the same.
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Where does meiosis take place and why?
Meiosis happens in the reproductive organs to produce cells that are haploid (gamete cells). Gametes (sperm/egg) are haploid so when they combine the resulting cell (the zygote) has the right number of chromosomes (46).
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What is the meaning of haploid?
Haploid cells are gamete cells and 'haploid' means that they only have one copy of each chromosome. Human body cells have 46 chromosomes, but haploid cells only have 23 so that when the gametes combine, 46 chromosomes are produced.
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What is the meaning of diploid?
Diploid cells, like human body cells, have a full set of 46 chromosomes. They have two versions of each chromosome - one from their mother and one from their father.
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Describe the first division of meiosis.
It duplicates it's DNA before it divides so that one arm of each chromosome is an exact copy of the other arm. The chromosomes line up in the centre of the cell and are then pulled apart so that each new cell only has one copy of each chromosome.
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Why is this important?
Having one copy of each chromosome means that some of the father's chromosomes and some of the mother's go into the new cell which creates variation in the offspring. If this didn't happen we would be weird clones.
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Describe the second division of meiosis.
The chromosomes line up again in the centre of the cell and the arms of the chromosomes are pulled apart, producing four haploid gametes, each with a single set of chromosomes in it.
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Card 2

Front

Why are proteins made in the ribosomes?

Back

DNA is needed to make proteins but it found in the cell nucleus and can't move out of it to reach the ribosomes in the cytoplasm as it's really big. This is therefore done using mRNA, which is like a messenger between the two.

Card 3

Front

Describe the process of transcription.

Back

Preview of the front of card 3

Card 4

Front

Describe the process of translation.

Back

Preview of the front of card 4

Card 5

Front

What is the more scientific name for protein?

Back

Preview of the front of card 5
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