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Revision 1. Molecules of life. Comparing cell structure. Usually sausage-shaped structures found in the cytoplasm of cells. They are often called the “powerhouses” of a cell because they are where most energy is released during respiration. The mitochondria. What’s in a cell?.
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Revision 1 Molecules of life
Usually sausage-shaped structures found in the cytoplasm of cells. They are often called the “powerhouses” of a cell because they are where most energy is released during respiration. The mitochondria
What’s in a cell? • Nucleus – contains genetic information, this is carried on chromosomes • Cell membrane – controls movement of substances in and out of the cell • Cytoplasm – where many chemical reactions happen • Mitochondria – cell respiration is carried out here. Energy is released from glucose in the presence of oxygen.
ENZYMES DIGESTS EGG MEMBRANE / PENETRATE / GET INSIDE THE EGG RESPIRATION
What is DNA? Chromosomes and their genes are made of a molecule called DNA. DNA stands for deoxyribonucleic acid. Each chromosome is a very long molecule of tightly coiled DNA. DNA molecules carry the code that controls what cells are made of and what they do. Which part of a DNA molecule holds this information?
A C G T DNA and base pairs The double helix ‘ladder’ of a DNA molecule is held together by ‘rungs’ made from pairs of chemicals called bases. There are four types of bases, and they are usually identified by their initials. adenine cytosine guanine thymine How do you think the four bases are paired?
A T C G How do bases pair together? Base pairs hold the two strands of the DNA helix together. The rules for base pairing are… ‘A’always pairs with ‘T’ ‘C’alwayspairs with ‘G’ There are millions of base pairs in a DNA molecule, and they always follow these rules. It is the sequence of these bases along a DNA molecule that forms the genetic code – it’s that simple!
DNA code • Found in the nucleus. Forms structures called chromosomes. A section of a chromosome is called a gene. Each gene is a code for making proteins. Our bodies need proteins to grow and make proteins. Everyone has his or her unique DNA code. • DNA – double helix; complimentary base pairs (adenine – thymine; cytosine – guanine) • Each time a cell divides the DNA copies itself. This is called DNA REPLICATION. The base pairs separate and the strand unzips to form two single strands. New bases pair up by complimentary base pairing to form two new double strands. • The order of bases found in a section of DNA is called the base code. Each THREE bases code for an amino acid. • E.g. AAA TAT CTC CCC TCA ACC GGG CGG TAA ATG (10 amino acids are coded for here) • The complimentary base pairs would be: • TTT ATA GAG GGG AGT TGG CCC GCC ATT TAC
DNA fingerprinting • Isolate blood of cell sample • Extract DNA • Use restriction enzymes to fragment the DNA • Place DNA fragments on gel • Apply and separate fragments using an electric current (electrophoresis) • Banding of DNA fingerprint can be matched.
DNA is cut into fragments DNA FRAGMENTS SEPARATED / ELECTRIC CURRENT APPLIED / ELECTROPHORESIS
3 CAT GAG ACT