Chapter 4: Patterns of Chapter 4: Patterns of HeredityHeredity

4.1 Living things inherit traits in patterns4.1 Living things inherit traits in patterns4.2 Patterns of heredity can be predicted4.2 Patterns of heredity can be predicted

4.3 DNA is divided during meiosis4.3 DNA is divided during meiosis4.4 Cells use DNA and RNA to make proteins4.4 Cells use DNA and RNA to make proteins

Before, you learned:Traits pass from parents to offspring in predictable patternsTraits are passed on through genesIn sexual reproduction, offspring get half their genes from each parent

4.4 Now, you will learn:How the structure of DNA stores information the cell needsHow DNA is copiedHow RNA uses the information from DNA to make proteins

Review (t/f)Review (t/f)

Genes are units of heredity that determine traitsGenes are units of heredity that determine traits TrueTrue A genotype refers to the observable A genotype refers to the observable

characteristics of an organismcharacteristics of an organism A phenotype refers to the observable A phenotype refers to the observable

characteristics of an organismcharacteristics of an organism A dominant trait is expressed only if two alleles A dominant trait is expressed only if two alleles

are present on a chromosomesare present on a chromosomes A dominant trait is expressed if one or two alleles A dominant trait is expressed if one or two alleles

are present on a chromosomeare present on a chromosome

4.4 Cells use DNA and RNA to make 4.4 Cells use DNA and RNA to make proteinsproteins

Template vs a copyTemplate vs a copy A:A:

B:B: Write a set of rules to describe how the characters Write a set of rules to describe how the characters

in line A related to the characters in line Bin line A related to the characters in line B Use the rules to produce a template Use the rules to produce a template

(corresponding pattern) that goes with:(corresponding pattern) that goes with: C: C:

A copy is a duplicate of what already exists. A copy is a duplicate of what already exists. A template forms a pattern that enables one to A template forms a pattern that enables one to

make a copy.make a copy.

DNA is the information DNA is the information moleculemolecule

DNADNA stores information stores information Like an instructional book: recipes for Like an instructional book: recipes for

food, model boats, card games, food, model boats, card games, computer gamescomputer games

The books don’t The books don’t do do these things, they these things, they hold the information, the instructions, hold the information, the instructions, that a cell needs to function/grow/dividethat a cell needs to function/grow/divide

ProteinsProteins do most of the work do most of the work

Proteins and Amino AcidsProteins and Amino Acids

ProteinsProteins: large molecules made up of chains of : large molecules made up of chains of amino acidsamino acids 20 different 20 different amino acidsamino acids combine to make up combine to make up

thousands of different thousands of different proteinsproteins found in humans found in humans Small: 129 amino acids; large: 2685 amino acidsSmall: 129 amino acids; large: 2685 amino acids

DNADNA: stores information for the cell to put : stores information for the cell to put together right sequences of together right sequences of amino acidsamino acids needed to produce specific needed to produce specific proteinsproteins

DNA DNA contains a “code” – set of rules and contains a “code” – set of rules and symbols – used to carry informationsymbols – used to carry information

DNA and the Genetic CodeDNA and the Genetic Code

Double-stranded Double-stranded spiral…twisted ladderspiral…twisted ladder

Nucleic acids (DNA and Nucleic acids (DNA and RNA) are made of RNA) are made of nucleotides:nucleotides: Nucleotide subunits Nucleotide subunits

make up the side rails make up the side rails and rungs (two bases)and rungs (two bases)

One nucleotide base One nucleotide base attaches to another attaches to another from the opposite strand from the opposite strand = “base pairs” = “base pairs”

DNA and the Genetic CodeDNA and the Genetic Code

Four different Four different nucleotides in DNA, nucleotides in DNA, identified by their identified by their bases:bases: Adenine (A)Adenine (A) Thymine (T)Thymine (T) Cytosine (C)Cytosine (C) Guanine (G)Guanine (G) ALWAYS: ALWAYS: AA - - TT and and CC – – GG ““All Tigers Can Growl”All Tigers Can Growl”

DNA and the Genetic CodeDNA and the Genetic Code

DNA, a molecule, contains information to DNA, a molecule, contains information to produce other molecules: proteinsproduce other molecules: proteins

Genes are a segment of DNAGenes are a segment of DNA

A set of bases specifies the A set of bases specifies the amino acidsamino acids needed to form a particular needed to form a particular protein:protein:

Triplet (3 bases) per 1 amino acid gives 64 possible Triplet (3 bases) per 1 amino acid gives 64 possible combinations (4*4*4)combinations (4*4*4)

Ex: T-C-T codes for arginineEx: T-C-T codes for arginine

A A genegene is the entire sequence of the is the entire sequence of the bases that codes for all the bases that codes for all the amino acidsamino acids in a in a proteinprotein Each gene is made up of a sequence of bases Each gene is made up of a sequence of bases

at a particular location on the DNAat a particular location on the DNA

proteins

Amino acids

Set of bases

Gene

DNA

ReplicationReplication Recall - Cell division: daughter cells receive an Recall - Cell division: daughter cells receive an

identical copy of the DNAidentical copy of the DNA DNA is copied before the cell divides: DNA is copied before the cell divides:

ReplicationReplication1.1. Two strands of DNA separateTwo strands of DNA separate

2.2. Nucleotides in the area around the DNA match up, Nucleotides in the area around the DNA match up, base by base (C-G and A-T)base by base (C-G and A-T)

3.3. Results in two identical DNA molecules, each with one Results in two identical DNA molecules, each with one strand of the each the old and new DNA strand of the each the old and new DNA

ReplicationReplication Each strand of DNA is used as a template Each strand of DNA is used as a template

(pattern or shape) to produce a copy of (pattern or shape) to produce a copy of the other strandthe other strand

RNA is needed to make RNA is needed to make proteinsproteins

DNA is not used to make proteins directlyDNA is not used to make proteins directly RNA (ribonucleic acid) RNA (ribonucleic acid)

Connects three bases (physically) to an amino acidConnects three bases (physically) to an amino acid carries the info from DNA to a ribosome where the amino carries the info from DNA to a ribosome where the amino

acids are brought together to form a proteinacids are brought together to form a protein DNA codes for RNA; 3 types:DNA codes for RNA; 3 types:

mRNA: messenger RNA – forms a copy of the DNA mRNA: messenger RNA – forms a copy of the DNA reciperecipe

rRNA: ribosomal RNA – brings together the other two rRNA: ribosomal RNA – brings together the other two types of RNA to form the amino acid chaintypes of RNA to form the amino acid chain

tRNA: transfer RNA – transfers an amino acid to the tRNA: transfer RNA – transfers an amino acid to the growing chain of amino acidsgrowing chain of amino acids

Has 3 bases on one end, can hold an amino aid on the other Has 3 bases on one end, can hold an amino aid on the other proteins

Amino acids

Set of bases

Gene

DNA

RNA is needed to make RNA is needed to make proteinsproteins

Prokaryotic cells: RNA and proteins Prokaryotic cells: RNA and proteins are both made in the cytoplasmare both made in the cytoplasm

Eukaryotic cells: DNA is copied in the Eukaryotic cells: DNA is copied in the nucleus, then RNA moves to the nucleus, then RNA moves to the cytoplasm where the proteins are cytoplasm where the proteins are mademade

TranscriptionTranscription

Transcription: the process of Transcription: the process of transferring information from DNA to transferring information from DNA to RNARNA

RNA similar to DNA: RNA similar to DNA: four types of nucleotide subunitsfour types of nucleotide subunits

3 bases: 3 bases: guanine (G),guanine (G), cytosine (C),cytosine (C), and and adenine (A)adenine (A)

44thth base NOT thyminne, it is base NOT thyminne, it is uracil (U)uracil (U)

TranscriptionTranscription

Transcription: the process of transferring information from DNA to RNATranscription: the process of transferring information from DNA to RNA

DNA is used like a template:DNA is used like a template: One side of DNA is used to make a One side of DNA is used to make a

complementary strand of mRNAcomplementary strand of mRNA **Only **Only individual genesindividual genes are transcribed, not are transcribed, not

the whole DNA molecule!the whole DNA molecule! DNA opens up just where the gene is locatedDNA opens up just where the gene is located Base pairs separateBase pairs separate Each base is joined by a matching base of mRNA (A-U Each base is joined by a matching base of mRNA (A-U

and C-G)and C-G)

TranscriptionTranscription

Different from replication:Different from replication: Only one strand of DNA is transcribed, Only one strand of DNA is transcribed,

so mRNA molecule is just a single strandso mRNA molecule is just a single strand When transcription is complete, mRNA is When transcription is complete, mRNA is

released and can be used again to make released and can be used again to make more copies of the gene in a short time!more copies of the gene in a short time!

At the end, the DNA molecule closesAt the end, the DNA molecule closes

TranslationTranslation

Replication and transcription pass Replication and transcription pass along information that is coded in the along information that is coded in the language of nucleotide baseslanguage of nucleotide bases

To make a protein, a cell must translate To make a protein, a cell must translate this language this language amino acids language amino acids language

Takes place in the cytoplasmTakes place in the cytoplasm Involves all three types of RNA: mRNA, Involves all three types of RNA: mRNA,

tRNA, rRNAtRNA, rRNA

TranslationTranslation Proteins are made on ribosomes (which are Proteins are made on ribosomes (which are

made of RNA and proteins)made of RNA and proteins) mRNA is a recipe for making one proteinmRNA is a recipe for making one protein

Ribosome is where the cooking gets doneRibosome is where the cooking gets done tRNA gathers the ingredients (amino acids)tRNA gathers the ingredients (amino acids)

tRNA shape can attaches to a specific amino acidtRNA shape can attaches to a specific amino acid Other end matches three bases that can match an mRNAOther end matches three bases that can match an mRNA tRNA does the actual translation of bases to amino acids tRNA does the actual translation of bases to amino acids

when it matches up with mRNAwhen it matches up with mRNA Ribosomes connect the amino acids and remove them Ribosomes connect the amino acids and remove them

from the tRNA moleculefrom the tRNA molecule

1. Translation begins when a 1. Translation begins when a ribosome attaches to the ribosome attaches to the beginning of an mRNA molecule.beginning of an mRNA molecule.

2. A tRNA molecule carrying an 2. A tRNA molecule carrying an amino acid joins up to a matching amino acid joins up to a matching triplet on mRNA on the ribosome.triplet on mRNA on the ribosome.

3. The ribosome attaches one 3. The ribosome attaches one amino acid to another as the amino acid to another as the ribosome moves along the mRNA ribosome moves along the mRNA molecule.molecule.

4. Each tRNA molecule is 4. Each tRNA molecule is released after the amino acid it released after the amino acid it carries is attached to the growing carries is attached to the growing chain of amino acids.chain of amino acids.

5. The ribosome completes 5. The ribosome completes translation when it reaches the translation when it reaches the end of the code for the protein. end of the code for the protein. The new protein molecule, made The new protein molecule, made of a chain of amino acids, is of a chain of amino acids, is released.released.

DNA replication, DNA replication, transcription, translationtranscription, translation

Process is basically the same in all cellsProcess is basically the same in all cells Flow of information goes from:Flow of information goes from:

DNA DNA RNA RNA protein protein Proteins are responsible for an Proteins are responsible for an

organism’s traits – you are a product of organism’s traits – you are a product of proteinsproteins

Proteins are made at different times for Proteins are made at different times for different purposes, all using different different purposes, all using different recipes in the DNA cookbook to carry recipes in the DNA cookbook to carry out the various functionsout the various functions

http://www.classroom20.com/video/video/show?id=649749%3AVideo%3A104840

24 minutes24 minutes

Shorter:Shorter: http://www.classroom20.com/video/video/s

how?id=649749%3AVideo%3A104840 http://www.youtube.com/watch?v=z7i879_

Lai8&feature=related