People and Terms YOU need to know!

What is the difference? Chromosome DNA Chromatin Gene Chromatid

Where can we find DNA? DNA up close! chromosome cell nucleus Double stranded DNA molecule DNA up close! Individual Nucleotides

Messages from the inside? DNA (Deoxyribonucleic Acid) is the genetic information of all living organisms stored in units called genes A gene is a sequence of DNA that codes for a protein These proteins make up our traits!!!

What about those alleles we learned about last time? Our traits (genes) are inherited by our ancestors, but how do those traits tell our bodies to look the way we look? It’s a code! (Like the Braille activity we did!) = CODE

Rosalind Franklin Took x-ray of what is now known as the DNA double helix Shared the Nobel Prize for aiding in discovery of the double helix of DNA

The Structure of DNA Using the information found by Rosalind Franklin, Watson & Crick developed the double helix model of DNA in 1953 The double helix consists of a backbone made of sugars and phosphates and alternating bases called nucleotides

Nucleotides A nucleotide is the monomer of DNA Nucleotides are small molecules made up of three parts A ribose (sugar) A phosphate group A nitrogenous group

DNA’s Four Nucleotides Adenine (A) Guanine (G) Cytosine (C) Thymine (T) Phosphate group Deoxyribose

Base Pairing Adenine always binds with Thymine (A-T) Cytosine always binds with Guanine (C-G)

Rungs of the Ladder are pairs of nitrogenous bases This is one example of the ladder being “untwisted” and how the bases are paired together

Let’s put it all together! Nucleotide Hydrogen bonds Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G)

Chromatin DNA and proteins in a non-structured form The term Chromatin = when the cell is not reproducing

Made up of DNA and proteins Chromosome Made up of DNA and proteins

Chromosome Chromatin

Chromatid ½ of a chromosome 2 chromatids = 1 chromosome TWO appear during the process of mitosis = SISTERS!

Contains hereditary information DNA Contains hereditary information Found in chromosomes

Gene “Instructions” Many genes within DNA Why we are who we are!

What does homologous mean? Homo = the same Hetero = different

Homologous The same!! We get ½ our chromosomes from … and ½ our chromosomes from

Mom Dad Homologous Pair Dad Mom

Who you callin' a diploid?? Haploid vs. Diploid Who you callin' a diploid??

*Total number of homologous pairs of chromosomes in a cell* Haploid *Total number of homologous pairs of chromosomes in a cell* What is the haploid number of human cells? 23

Total number of chromosomes in a cell Diploid Total number of chromosomes in a cell What is the diploid number of human cells? 46

Haploid vs. Diploid The reference to haploid cells is 1N The reference to diploid cells is 2N If N = 23 for humans (haploid) Then 2N ( 2 x 23 ) = 46 (diploid) Get it??

Sex chromosomes vs. Autosomes Sex chromosomes = this is what determines our sex (duh!) Autosomes = all the other chromosomes

Humans have 1 pair of sex chromosomes and 22 pairs of autosomes X and Y (male) X and X (female)

Any questions??