Take out a piece of paper. Fold it in thirds Take out a piece of paper. Fold it in thirds. Write observations at the top of one column, inferences at the top of the next, and predictions at the top of the last.

These two girls are twins. How could they look so different?

Independently and quietly, draw a model of how you think these twins came to be.

Our bodies are made up of over 37 trillion cells How many cells do you think are in the human body? Hypothesize, and write down what you think! Our bodies are made up of over 37 trillion cells

Each cell in our bodies contains genetic information called DNA that dictates many things, one of which is what we look like.

DNA is the genetic material that makes us who we are; what we look like, our strengths and weaknesses, our personality, etc. DNA, or deoxyribonucleic acid, is a long string like material called chromatin. To make all this information easier to store, the DNA is coiled into chromosomes.

DNA… starts off as this… then it coils to this! Into a chromosome

DNA wraps around proteins to help condense it. DNA double helix DNA and histones Chromatin Supercoiled DNA Chromatids Centromere This is a duplicated chromosome

Are there different types of chromosomes? Humans and animals have 2 different types. Sex chromosomes: Either X or Y Determine gender Females are XX Males are XY Autosomes: All other chromosomes in an organism

Humans….. ….have 2 sex chromosomes and 44 autosomes How many total chromosomes are there? How many pairs of chromosomes are there?

Every cell, except sex cells, have 2 copies of each autosome Every cell, except sex cells, have 2 copies of each autosome. Where did they come from? These copies are called homologous chromosomes. They have the same size and shape. They carry genes for the same traits. How many pairs of homologous chromosomes do you have in your body cells?!

Diploid Haploid Have 2 sets of chromosomes (both chromosomes in a homologous pair) Body cells Have 1 set of chromosomes Sex cells (gametes/sperm and egg cells)