Genetics Unit –Cell Reproduction

Asexual reproduction – Binary fission – Mitosis

Sexual reproduction – Meiosis

Meiosis I, meiosis II gametes

Genetics Unit – Chpt. 9Punnett Squares

Probability Punnett square

– Monohybrid, dihybrid– Dominant, recessive, homozygous,

heterozygous– Incomplete, Co-dominant and x-linked traits

Genetics Unit –Gregor Mendel

Father of modern genetics– 1st to apply mathematics of statistics to

crosses, 1840’s, Austria, monastery gardens

Genetics field of biology devoted to understanding HOW characteristics are transmitted from parents to offspring

Heredity the transmission of characteristics from parents to offspring

Mendel’s Laws

1. Law of Segregation : pair of factors is separated during the formation of gametes

2. Law of Independent Assortment : factors for different traits are distributed to gametes independently

Molecular Genetics

Molecular genetics is the study of the structure and the function of the chromosomes and the genes.

This would include mapping the genome, locating markers for diseases, making proteins and technology like cloning, genetic engineering and DNA fingerprinting.

Genetics Unit- Nucleic acids and protein synthesis

DNA – organic compound made of repeating subunits called nucleotides.

A DNA nucleotide has three parts– Sugar (deoxyribose)– Phosphate group (PO4)

– Nitrogen containing base (A,T,C,G)

Adenine, thymine, cytosine and guanine

Watson and Crick

James Watson and Francis Crick are the discoverers of the DNA double helix

1953, Cambridge, England Built a wooden model based on other

research , including x-ray crystallography Other scientists involved where; Rosalind

Franklin, Linus Pauling, Maurice Wilkins

Complementary Base Pairing

Because of the exact shape and size of the DNA, the sugars and phosphates make the ‘sides of the ladder’ and the nitogenous bases make the ‘rungs.

A and G (purines) are larger than C and T (pyrimidines)

MUST PAIR UP with A-T and C-G so all rungs are the same length.

A-T and C-G are hydrogen bonds.

DNA Replication

During the S portion of interphase

All DNA is copied so there are 2 complete sets, one set for each new cell

p.188

DNA helix is untwisted by helicase enzyme

DNA polymerase enzymes add new bases

Get two identical strands of double helix

Mutations

Change in the nucleotide sequence 1 error per 100,000 bases, VERY accurate Proof reading enzymes correct – allowing

for 1 per billion nucleotide average Changes can also be caused by

‘mutagens’ like chemicals and radiation

RNA

Single stranded Copies of DNA Can leave nucleus Takes DNA code to the ribosomes so that

proteins can be manufactured Contains the sugar ribose, and the bases

A, C, G and U (uracil). There is no T in RNA

RNA Transcription

DNA is opened, only at the gene/region of interest. A “copy” is made by matching A-U and C-G The mRNA (leaves) and the DNA reseals. Original

DNA is intact, undiluted, unchanged and in the nucleus.

RNA strand is EDITTED to delete unnecessary regions called introns and the ‘good regions are spliced together (exons) and make the final mRNA

Types of RNA

mRNA – messenger, carries DNA info from the nucleus to the cytoplasm

tRNA – transfer (transport), short chain, highly folded, binds specific amino acids to the mRNA

rRNA – ribosomal, most abundant version, ribosomes are made of protein and rRNA.

Translation of RNA into protein

“protein synthesis” mRNA is read by the ribosome in chunks Each region of 3 bases on the mRNA is

called a codon (p.194) Each codon signals a specific amino acid If you put the right amino acids in the

right order you have ….. A protein.

Remember…..

“Every thing, in every cell, is either made of a protein or run by a protein.”

Functions of proteins include – muscle, structure, storage, immunity, identification, communication, and transport

Genetics Unit – Chpt 11Gene Expression

Gene expression – all genes are not ‘on’ all the time. The process of turning on the right genes at the right time is gene expression

Genome – complete set of genetic material for an individual

Operons

Found in bacteria cells – very different machinery from our cells

Jacob and Monad Operon = structural genes + promoter +

operater Operons can

– 1. repress protein production (repressor)– 2. activate protein production (inducer)

More Chpt. 11 vocabulary

Cell differentiation – the development of cells that have specialized functions ( muscle, nerve, skin, etc.)

Morphogenesis – the formation of an organism, getting the tissues and organs in the right places

Homeotic genes – regulatory genes that determine where anatomical features go

CANCER

Malignant tumors are usually called cancer. Tumor – abnormal proliferation of cells,

uncontrolled cell division Benign tumor – mass of cells Malignant tumor – uncontrolled cell division

that invades and destroys healthy tissue Metastasis – spread of cancer to new sites

Cancer continued

Oncogenes – genes that “cause” cancer, code for uncontrolled cell growth

Tumor suppressor genes – code for proteins that prevented uncontrolled cell division.

Mutation of tumor suppressor genes cause a predisposition to cancers

Some cancers are now directly linked to viruses as their “cause” .