B5 - Growth And Development Flashcards
How do the four bases of DNA pair up?
A–T and C–G. This is called base pairing.
What does DNA control?
The production of proteins in a cell.
What is a gene?
A section of DNA that contains the instructions for one particular protein.
How do cells make proteins?
By joining amino acids together in a particular order. It’s the order of the bases in a gene that tells the cell in what order to put the amino acid’s together. Each set of three bases (called a triplet) codes for one amino acid.
Where are proteins made and what are they made by?
Proteins are made in the cell cytoplasm by organelles called ribosomes.
Explain how a copy of the DNA is made using a molecule called messenger RNA to get the information to the ribosomes
The two DNA strands on zip, a molecule of messenger RNA is made using one strand of DNA as a template. Based pairing ensures it’s an exact match. The messenger RNA molecule moves out of the nucleus and joins the ribosome in the cytoplasm. The job of the ribosome is to stick amino acids together in a chain to make a protein, following the order of bases in the messenger RNA.
Describe a DNA molecule?
Two strands coiled together in the shape of a double helix. Each strand is made up of lots of small units called nucleotides. Each nucleotide contains a small molecule called a base. DNA has just for different bases – adenine(A), cytosine(C), guanine(G) and thymine(T). The two strands are held together by the bases.
Cells are needed for growth and repair, what happens when cells are grow and divide?
First the cell physically grows and duplicates its contents, then it splits into two by mitosis.
How are chromosomes copied?
Molecule of DNA splits. Bases on free-floating nucleotides pair up with matching bases on DNA. Cross-links between the bases and the old DNA strands, and the nucleotides are joined together.
How does a cell split by mitosis?
The cell has two copies of DNA spread out in long strings. The DNA forms X-shaped chromosomes, each arm is identical. Chromosomes line up at the centre of the cell and cell fibres pull them apart, the two arms go to opposite ends of the cell. Membranes form around each at of chromosomes, this forms the nucleus of the two new cells. Lastly the cytoplasm divides.
