Nucleus directs cell activities through chromosomes (long strand of DNA) DNA = molecule that stores genes = ‘programming’ for cell structures + activities. Nuclear membrane allows materials to pass into/out of nucleus Nucleolus = site for production + assembly of ribosomes (make proteins) Rough endoplasmic reticulum has ribosomes attached, transports proteins Smooth Endoplasmic Reticulum no ribosomes, manufactures + transports fats Cytoplasm contains specialized microtubules (assist movement of organelles) called centrioles.

DNA deoxyribonucleic acid Is your friend….

Lesson objectives Know what DNA is Understand the structure of DNA Know what the ‘base pairs’ are Know the difference between dominant and recessive genes

DNA molecule = two strands of smaller molecules, called nucleotides. The sides of the DNA ladder are made of the sugar and phosphate molecules joined to each other.

There are four different nitrogenous bases: adenine (A), thymine (T), cytosine (C), and guanine (G). Pairs of these bases form each rung of the DNA ladder. – Adenine always pairs with thymine (A-T) – cytosine always pairs with guanine (C-G) These are sometimes referred to as base pairs.

Before a cell divides, each DNA molecule makes a copy of itself. Each DNA molecule splits in many places between the pairs of bases, like a broken zipper. New bases join up with the bases on each of the opened sides of the ladder to form two identical DNA molecules

Dominant or recessive? We all have genes in our DNA which aren’t expressed, but could be passed on to our children You might have a gene for red hair (which is recessive) and a gene for brown hair (which is dominant), so you would have brown hair The most common traits people have are the result of dominant genes.

Conduct an experiment to determine a dominant and recessive gene 1.Make a prediction (for example, I predict that the gene for straight hair is dominant and the gene for curly hair is recessive). 2.Collect Data- walk around the classroom and survey your classmates. 3.Conclusion- What are the results? Did the data support your prediction? 4.Verify your results- research genes and find out whether your results reflect reality.