Science 10 BIOLOGY UNIT WHAT IS GENETICS Genetics

Science 10 BIOLOGY UNIT WHAT IS GENETICS?

Genetics • Genetics is the study of heredity. • Heredity is where a parent passes certain genes to their offspring. • Every child inherits genes from both of their biological parents and these genes in turn express specific traits. • Traits are observable characteristics determined by specific segments of DNA called genes.

Examples of Genetic Traits • Freckles, • Hair colour • Curly hair • Dimples • Handedness • Red/green colourblindness

Genetic Traits Treasure Hunt

Inside the Nucleus What do you remember from Grade 9?

Label the cell

What does the nucleus do? • Directs all of the cell’s activities – • ability to grow, develop and replicate (make copies of itself) What’s inside the nucleus? • Our genetic information in a long molecule called DNA • Nucleolus

Nucleolus • The nucleolus is a round body located inside the nucleus • assembles ribosomal subunits • makes ribosomal RNA (r. RNA). It then sends the subunits out to the rest of the cell where they combine into complete ribosomes.

How does the nucleus perform it’s job? • Inside the nucleus are the instructions for how to perform all cell activities are carried in molecules of DNA.

DNA the book of you • Ted Ed video • https: //ed. ted. com/lessons/dna-the-book-of-you-joe-hanson • Ameoba Sisters DNA • https: //www. youtube. com/watch? v=_POd. Wsii 7 AI

What is DNA? • DNA stands for Deoxyribonucleic acid • Contains our genetic material - the stuff that determines all our inherited traits; • controls the production of proteins • DNA is found tightly packed in nucleus as chromatin • chromatin condenses to visible chromosomes when a cell is ready to divide • There is an exact copy of DNA in almost every cell

DNA Structure • DNA exists as a double helix, a long, two stranded molecule like a twisted ladder.

How was the structure of DNA discovered? • In the early 1950 s two scientists, Rosalind Franklin and Maurice Wilkins, studied DNA using x-rays. • Franklin produced an x-ray photograph that allowed two other researchers, James Watson and Francis Crick to work out the 3 D structure of DNA. The structure of DNA was found to be a Double helix (twisted ladder). http: //ed. ted. com/lessons/rosalind-franklin-dna-s-unsung-hero-claudio -l-guerra

What is DNA made of? • DNA is made of repeating units called nucleotides • Each nucleotide is composed of three parts: • Phosphate group • Sugar (pentose) • Nitrogenous base • The sugar and phosphate make up the “sides” of the ladder

Nitrogenous bases • The bases pair up in the middle, forming the “rungs”of the ladder. • Hydrogen bonds between the nitrogenous bases hold the two strands of DNA together.

Nitrogenous Bases • There are four different nucleotides because there are four different bases: • adenine (A), • guanine (G), • cytosine (C), • thymine (T) • two types of bases: • purines – A, G have a double ring structure • pyrimidines – C, T, have a single ring structure

Complementary Base Pairing: • A with T • C with G • Chargaffs Rule: • the amount of A = T, C = G

What part of DNA makes up our genetic code? • It is the sequence of these bases that determines our genetic code. • Our genetic code determines • what proteins are produced and • What traits we have

Genes • They are basic units of heredity: determine our traits and protein production • Genes are segments of DNA that code for a particular protein. • Genes vary in size from a few hundred DNA bases to more than 2 million bases • Humans have about 23, 000 genes • Video Stated Clearly: What is a gene? https: //www. youtube. com/watch? v=5 MQd. Xj. RPHm. Q

Genes • Genes always occur in pairs: Because we have 2 sets of chromosomes (one from mom, one from dad), • Alleles are forms of the same gene with small differences in their sequence of DNA bases.

Putting it all together • Genes are segments of DNA. • DNA exists as a long molecule tightly coiled into chromosomes. • Chromosomes are found in the nucleus of every cell.

How many chromosomes do we have? • Humans have 23 pairs of chromosomes (haploid number) for a total of 46 (diploid number). • 22 of these pairs are autosomes, • 23 rd pair, the sex chromosome • Females have XX • Males have XY Karyotype

Sex Determination: More Complicated than you thought • Ted Ed video • https: //ed. ted. com/lessons/sex-determination-more-complicatedthan-you-thought

Build your own DNA HW: WB p 58 -60 DNA Worksheet

Do all cells have DNA?

How does DNA get into new cells? When cells divide, every new cell needs a copy of the DNA to carry the instructions of how to be a cell. DNA replicates (copies) itself right before a cell divides. Ameoba Sisters DNA Replication : https: //www. youtube. com/watch? v=5 q. Srmei. Wsuc&vl=en

How can each cell have the same copy of DNA? DNA REPLICATION: the process by which DNA copies itself before a cell divides • DNA Replication is Semi-Conservative: • Each new piece of DNA is made up of 1 old strand 1 new strand. • This ensures accurate replication.

DNA Replication 1. DNA helix unwinds 2. Complementary nucleotides attach, elongating each strand 3. Result is two new DNA molecules identical to the original, each with one new strand one old.

The sequence of bases that determines the trait or protein.

What is the importance of proteins? • Proteins are made up of smaller building blocks called amino acids, joined together in chains. • Proteins are molecules that all the cells of the body need in order to work properly. • They determine the characteristics of the organism. • Some proteins are parts of cell structures (collagen, keratin, elastin) • Some drive chemical reactions within the body (enzymes) • Some are messengers (hormones). • Some are in our blood (hemoglobin, antibodies, clotting factors) • Humans have as many as 100 000 proteins.

Where are proteins made? • Proteins are made in the cytoplasm of the cell by ribosomes. • Ribosomes are made in the nucleolus and then move to the cytoplasm.

How does the genetic code become protein? (How is a gene expressed? ) Gene Expression: DNA Transcription and Translation

Gene Expression Gene expression is the translation of genetic code into the production of a protein • occurs in processes: Transcription (in nucleus) and Translation (outside nucleus)

From genetic code to protein • DNA remains in the nucleus but proteins are made in the cytoplasm of the cell. • How does the code get to the ribosomes where the protein is made? • The message must be copied and carried out of the nucleus. • RNA is the messenger

RNA • RNA is ribonucleic acid • Like DNA, it is also a strand of nucleic acids except: • it is single-stranded, • instead of thymine it uses Uracil to pair with adenine. • It’s sugar is ribose instead of deoxyribose • m. RNA is called messenger RNA because it takes the copied message out to the ribosomes to make protein.

Difference between RNA and DNA STRUCTURE: Strands of nucleotides Sugars Nitrogen Bases DNA RNA Double Single Deoxyribose Ribose Thymine Uracil

Video Amoeba Sisters RNA • https: //www. youtube. com/watch? v=0 Elo-z. X 1 k 8 M&list=PLMqhdan 0 q. YVBC 8 ILBb-AQKf. NNRm. BM 0 N-

Video • Amoeba Sisters Protein Synthesis • https: //www. youtube. com/watch? v=h 5 m. Jb. P 23 Buo