Download Genetics Unit – Chpt. 8 Cell Reproduction

Genetics Unit –Cell Reproduction
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Asexual reproduction
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Binary fission
Mitosis
Sexual reproduction
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Meiosis
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Meiosis I, meiosis II
gametes
Genetics Unit – Chpt. 9
Punnett Squares
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Probability
Punnett square
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Monohybrid, dihybrid
Dominant, recessive, homozygous,
heterozygous
Incomplete, Co-dominant and x-linked traits
Genetics Unit –
Gregor Mendel
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Father of modern genetics
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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
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Law of Segregation : pair of factors is
separated during the formation of
gametes
Law of Independent Assortment :
factors for different traits are distributed
to gametes independently
Molecular Genetics
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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 UnitNucleic acids and protein synthesis
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DNA – organic compound made of
repeating subunits called nucleotides.
A DNA nucleotide has three parts
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Sugar (deoxyribose)
Phosphate group (PO4)
Nitrogen containing base (A,T,C,G)
Adenine, thymine, cytosine and guanine
Watson and Crick
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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
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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
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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
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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
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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
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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
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“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 11
Gene Expression
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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
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Found in bacteria cells – very different
machinery from our cells
Jacob and Monad
Operon = structural genes + promoter +
operater
Operons can
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1. repress protein production (repressor)
2. activate protein production (inducer)
More Chpt. 11 vocabulary
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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
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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
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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” .