DNA Replication

SC.912.L.16.3

Describe the basic process of DNA replication and how it relates to the transmission and conservation of the genetic information.

Source: http://genes.atspace.org/1.4.html

What do I need to know? the basic process of DNA replication and

how it relates to the transmission and conservation of genetic information

that mutations in the DNA sequence may or may not result in phenotypic change and how mutations in gametes may result in phenotypic changes in offspring

the basic processes of transcription and translation and how they result in gene expression

the basic processes of DNA are universal in organisms

that similarities in the genetic codes of organisms are due to common ancestry and the process of inheritance

Blame it on.. DNAVideo - Key Vocabulary DNA RNA transcription translation amino acid protein cytoplasm ribosome nitrogen bases mutation

Structure of DNA DNA is made of subunits

called nucleotides

DNA nucleotides are composed of a phosphate, deoxyribose sugar, and a nitrogen-containing base

The 4 bases in DNA are: adenine (A), thymine (T), guanine (G), and cytosine (C)

Source: http://bootstrike.com/Genetics/DNA/images/structure.gif

DNA Replication

Source: http://y12hb.files.wordpress.com/2013/03/semi-conservative.png

Think About This… DNA is only found in

the nucleus

Who we are, how we look, and the mechanisms that make are body function are all determined by proteins

Proteins are only made in the ribosome.

Source: http://www.biologycorner.com/resources/DNA-RNA.gif

Why do we need both DNA and RNA?

DNA holds all the genetic information

DNA damage = mutation

Safer in the nucleus

RNA acts as messenger

Source: http://classconnection.s3.amazonaws.com/333/flashcards/903333/png/transcription_-_translation1320698154407.png

Protein Synthesis: The Central Dogma

DNA vs. RNA

Source: http://i.qkme.me/365r3l.jpg

type of sugar bases # of strands

Types of RNA

Source: http://crescentok.com/staff/jaskew/isr/anatomy/anatomy1/mrna.gif

Type Function

Messenger RNA (mRNA)

Carries copies of the instructions for assembling amino acids from DNA to the rest of the cell

Ribosomal RNA (rRNA)

Is a part of ribosomes

Transfer RNA (tRNA)

Transfers each amino acid to the ribosome to help assemble proteins

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Transcription

Source: http://i.qkme.me/365r3l.jpg

the making of messenger RNA (mRNA) from DNA in the nucleus

DNA unwinds and mRNA is made complementary to the DNA A=U G=C

3 nitrogen bases in mRNA is called a codon

Translation

Source: http://hyperphysics.phy-astr.gsu.edu/hbase/organic/translation.html

Involves 20 different amino acids in the sequence given by the three-base codons built from an alphabet of four bases

the process in the ribosome builds the polypeptide chains that will become proteins

Genetic CodeThe Language of Proteins

Source: http://cronodon.com/BioTech/Ribosomes.html

each 3 nucleotide sequence in an mRNA strand is called a codon codes for a 1 amino acid codes for an amino acid using

specific rules there are 64 (43) possible

codes, but only 20 amino acids

more than 1 triplet may code for the same amino acid

note that several codons can also act as start (AUG) or stop (UAA) signals

Activity: Transcribe & Translate a Gene

Mutations Mutation: change in

DNA

if a base is substituted or deleted, the triplet(s) are different

this sometimes leads to difference in the protein

Basic Process of DNA is Universal

Mutation: change in DNA

if a base is substituted or deleted, the triplet(s) are different

this sometimes leads to difference in the protein

Show What You KnowGenes for medically important proteins can be cloned and inserted into bacteria, as shown in the diagram below.

Why can bacteria recognize a human gene and then produce a human protein?

A. DNA replication in bacteria and humans is the same.

B. Bacterial cells contain the same organelles as human cells.

C. The basic components of DNA are the same in humans and bacteria.

D. Bacterial cells and human cells contain the same kind of chromosomes.

Show What You KnowA cell is replicating its DNA. Part of the DNA strand reads ACCGTAC. The new strand built off this segment reads TGGAATG. What effect might this have when the DNA replicates in the future?

A. Cells having the new DNA version will look or operate differently from cells with the original DNA.

B. Only the sections of DNA without mistakes will be used in the future so the DNA strand will shorten.

C. The DNA will be exactly like the original since only the original strand of DNA is used as a template.

D. When the new strand is used as a template the strand built from it will differ from the original DNA.

Show What You Know

Which of the following processes produces the nucleotide sequence UUA from the sequence AAT?

A.meiosis

B. replication

C.respiration

D. transpiration

Show What You KnowWhen an extra nitrogenous base is inserted into the DNA sequence of a gene, the protein product of the gene is usually nonfunctional. Which of the following statements best explains why?

A. The inserted base increases the rate of translation in the corresponding mRNA sequence.

B. The inserted base causes the DNA sequence to be transcribed into the RNA in the opposite direction.

C. The inserted base causes the codons in the mRNA sequence to be incorrect for the desired protein.

D. The inserted base signals enzymes to translate the DNA sequence rather than the RNA sequence into the protein.

Show What You KnowThe diagram to the right represents a process that occurs in the nucleus of a eukaryotic cell.

Which of the following statements describes what is happening in this process?

A. Molecules of RNA are forming chromosomes.

B. A molecule of mRNA is directing the production of tRNA.

C. Molecules of DNA are being packaged for export to the ribosomes.

D. A molecule of DNA is being replicated to make two identical copies.