The genome is the full set of genetic information that an organism carries in its DNA A karyotype shows the complete diploid set of chromosomes grouped together in pairs, arranged in order of decreasing size

A human has 2 sets of 23 chromosomes – 46 in total – 2 of which are sex chromosomes – XX in females and XY in males (Y is much smaller) – Autosomal chromosomes or autosomes are the other 44

Many human traits follow a pattern of simple dominance – Rh blood group (+ or -)

Other human genes display codominant inheritance – ABO blood group (A & B being codominant)

Other genes may be located on the X or Y sex chromosomes, making them sex-linked genes – If it involves only the Y, the disease is present in males – If it involves the X, the disease is present in males, females may be carriers or have the disease

How is a female a carrier and not affected? X chromosomes inactivation – One of the X’s in females (usually the bad one) is turned off – Males cannot do this because they only have one X which is important for normal development

You can use a pedigree (chart that shows relationships within the family) to figure out a traits pattern of inheritance – Inferring the genotypes helps to explain how the disease is transmitted

Frederick Griffith wanted to figure out how bacteria makes people sick – particular pneumonia Experimented with something called transformation the passing of DNA from one bacteria to another – Came to this conclusion because the harmless bacteria (heat- killed were transformed into harmful bacteria (disease- causing) if placed in the same area: even if heat killed!

By observing bacteria transformation, Avery and other scientists discovered that the nucleic acid DNA stores and transmits genetic information from one generation of bacteria to the next Hershey & Chase later experimented with bacteriophages – a virus that infects bacteria

Hershey & Chase studied the bacteriophage and looked at whether the virus injected its protein or DNA – they confirmed that DNA was the genetic material found in all living cells

The DNA that makes up genes must be capable of storing, copying, and transmitting genetic information in a cell – Very important that during meiosis, there is no loss of DNA – that would be losing valuable information!

DNA is a nucleic acid made up of nucleotides joined into long strands or chains by covalent bonds – Nucleotides are the building blocks of nucleic acids and are made up of a sugar, a phosphate group, and a nitrogenous base

DNA has 4 kinds of nitrogenous bases: – Adenine – Thymine – Cytosine – Guanine – A==T ; C==G (Chargaff’s rule) – These bases can be strung together in many different sequences to give different information

The clues in Franklin’s X-Ray pattern enabled Watson and Crick to build a model that explained the specific structure and properties of DNA – DNA is a twisted ladder (double-helix) that runs anti-parallel and has specific base pairing (A==T, C==G)

Each strand of DNA is complementary to the other – therefore, it has all the info needed to reconstruct the other half during replication (late interphase)

Steps for DNA Replication: – DNA strand unzips – DNA Polymerase (an enzyme) joins individual nucleotides according to base pairing to produce a new strand of DNA on both strands – DNA Polymerase checks for errors “proofreads” – 2 new identical DNA strands are created

Telomeres (tips of chromosomes) are particularly hard to replicate – Telomerase help to prevent genes from being damaged or lost during replication by being in charge of the ends – In adult cells, telomerase barely works. In new stem cells or cancer cells, telomerase is on overdrive

Prokaryotes Circular DNA in cytoplasm Replication starts from a single point and proceeds in 2 directions until it’s all copied Eukaryotes DNA in chromosomes in nucleus Replication can start at hundreds of places, proceeding in both directions until completed copied

Sometimes, DNA Polymerase doesn’t catch all of the errors and damaged regions of DNA are copied – leads to cancer or cell death