Presentation is loading. Please wait.

Presentation is loading. Please wait.

Gene Action and Expression

Published byHope Bates Modified over 5 years ago

Similar presentations

Presentation on theme: "Gene Action and Expression"— Presentation transcript:

1 Gene Action and Expression
Chapter 10 Gene Action and Expression

2 Central Dogma DNA is the genetic material within the nucleus.
Cytoplasm Nucleus DNA DNA is the genetic material within the nucleus. Replication The process of replication creates new copies of DNA. Transcription The process of transcription creates an RNA using DNA information. RNA Translation The process of translation creates a protein using RNA information. Protein

3 Two types of nucleic acids
# of strands kind of sugar bases used

4 Two types of nucleic acids
RNA Carries protein- encoding information Can be catalytic DNA Carries RNA- encoding information Not catalytic

5 Types of RNA mRNA Messenger RNA encodes protein
rRNA Ribosomal RNA part of ribosome,used to translate mRNA into protein tRNA Transfer RNA couples the region which binds the mRNA codon and its amino acid

6 rRNA is part of ribosome, used to translate mRNA into protein

7 tRNA is a connection between anticodon and amino acid

8 The genetic code There is a 3 to 1 correspondence between RNA nucleotides and amino acids. The three nucleotides used to encode one amino acid are called a codon. The genetic code refers to which codons encode which amino acids.

9 The genetic code

10 A codon of three nucleotides determines choice of amino acid

11 The genetic code is non-overlapping

12 The genetic code is universal
All known organisms use the same genetic code. (Rare organisms use one codon for an additional amino acid.) The genetic code is degenerate Some codons encode the same amino acid. e.g. GGU, GGC, GGA, and GGG all encode glycine Degeneracy is mostly at the third base of the codon. Some codons have additional functions AUG encodes methionine. Methionine can be used within a protein sequence and is often the first amino acid cueing the beginning of translation. UAA, UAG, and UGA do not encode an amino acid These codons signal termination of the protein.

13 Transcription Three step process: Initiation
Control of transcription is regulated by transcription factors. Elongation RNA polymerase adds nucleotides to growing RNA. Termination Sequences in the DNA prompt the RNA polymerase to fall off ending the transcript.

14 Initiation of transcription
Transcription begins at regions called the promoters. The promoter recruits TATA protein, a DNA binding protein, which in turn recruits other proteins. TATA binding protein Promoter Gene sequence to be transcribed TATA box DNA GG TATA CCC Transcription factor Transcription begins When a complete transcription complex is formed RNA polymerase binds and transcription begins.

15 Transcription DNA is used as a template for creation of RNA using
the enzyme RNA polymerase. DNA 5’ G T C A T T C G G 3’ 3’ C A G T A A G C C 5’

16 Transcription RNA polymerase reads the nucleotides on the template strand from 3’ to 5’ and creates an RNA molecule that looks like the coding strand. DNA DNA coding strand 5’ G T C A T T C G G 3’ 3’ C A G T A A G C C 5’ DNA template strand

17 Transcription DNA DNA coding strand 5’ G T C A T T C G G 3’ G RNA 5’ U
DNA template strand

18 mRNA processing mRNA transcripts are modified before use as a
template for translation: Addition of capping nucleotide at the 5’ end Addition of polyA tail to 3’ end Important for moving transcript out of nucleus And for regulating when translation occurs Splicing occurs removing internal sequences introns are sequences removed exons are sequences remaining

19 mRNA processing

20 Gene Expression Together transcription and translation are called gene expression. The genetic information encoded in the DNA of an embryo includes all of the genes needed to develop and maintain the organism. Different cell types express different subsets of genes. Differential gene expression during development establishes the role of a cell within the body.

21 Translation The process of reading the RNA sequence of an mRNA and creating the amino acid sequence of a protein is called translation. DNA T C A G template strand Transcription mRNA A G U C Messenger RNA Codon Translation Protein Lysine Serine Valine Polypeptide (amino acid sequence)

22 Translation is composed of three steps
Initiation translation begins at start codon (AUG=methionine) Elongation the ribosome uses the tRNA anticodon to match codons to amino acids and adds those amino acids to the growing peptide chain Termination translation ends at the stop codon UAA, UAG or UGA

23 Translation initiation

24 Initiation Complex Small ribosomal subunit mRNA 5’ 3’ A U G C Leader sequence Met U A C Initiator tRNA Assembling to begin translation tRNA of methione hydrogen bonds with the anticodons UAC at the start codon AUG on the mRNA small rRNA subunit

25 Translation Elongation
Ribosome mRNA 5’ 3’ U C G A C U A C U tRNA Amino acid Met Gly Large ribosomal subunit

26 Translation Elongation
Large rRNA subunit attaches to the small rRNA subunit tRNA of the second amino acid complementary to the second triplet code attaches by H bonds Enzyme catalyzes the dehydration synthesis reaction between the two amino acids MettRNA is released and leaves the complex to go back and get recharged with more met.

27 Translation Elongation
C U A Met mRNA 5’ 3’ Gly G Cys

28 Translation Elongation
The rRNA complex moves one triplet space The third charged tRNA attaches by the anticodons to the third triplet codon on mRNA These steps are repeated and amino acids are bonded to make the protein sequence

29 Translation Elongation
mRNA 5’ 3’ U C G A A C Cys C U Gly C U A Met

30 Translation Elongation
mRNA 5’ 3’ U C G A C U Gly A C Cys C U A C U Lys Met

31 Translation Elongation
mRNA 5’ 3’ U C G A A C Cys C U Lys C U Met Gly Lengthening polypeptide (amino acid chain)

32 Translation Elongation
mRNA 5’ 3’ U C G A A C Cys C U Lys C U C U G Arg Met Gly

33 Translation Elongation
mRNA 5’ 3’ U C G A A C Cys C U Lys C U C U G Arg Met Gly

34 Translation Elongation
Stop codon mRNA 5’ U C G A U A C U Lys C U G Arg A C Met Gly Cys Release factor

35 Translation Termination
Stop codon Ribosome reaches stop codon mRNA 5’ U C G A U A C U G Arg C U Release factor Met Gly Cys Lys

36 Translation Termination
Once stop codon is reached, elements disassemble. U C G A C U G Release factor Met Gly Cys Lys Arg

37 Translation Termination
Elongation continues till the stop codon is reached A release factor attaches to the stop codon The rRNAs and mRNA complex is broken Protein released

38 Translation: multiple copies of a protein are made simultaneously

39 Levels of protein structure
Primary structure sequence of amino acids Secondary structure shapes formed with regions of the protein (helices, coil, sheets) Tertiary structure shape of entire folded protein due to interactions between particular peptides Quaternary structure structures formed by interaction of several proteins together e.g. Functional hemoglobin is two alpha-hemoglobin proteins and two beta-hemoglobin proteins form a heterotetramer

40 Levels of protein structure

41 Misfolding of protein impairs function
Misfolded prion protein disrupts functions of other normally folded prion proteins. Aberrant conformation can passed on propagating like an “infectious” agent.

42 Human Genome 3.2 million DNA base pairs
1.5% encode proteins < = > % not protein encoding ~ 31,000 genes encoding 100, ,000 proteins How are 100,000 to 200,000 proteins produced from 31,000 genes? What is the 98.5% of the human genome that does not encode proteins?

43 Alternative splicing of exons forms distinct proteins: one gene, many proteins

44 Exon shuffling forms distinct proteins: several genes, multiple proteins

45 Noncoding portion of the human genome
Type of sequence Function or characteristic Noncoding RNAs Translation (tRNA,rRNA) Pseudogenes RNA processing Introns Removed with RNA processing Promoters and other regulatory regions Determine when and where transcription occurs Repeats: Transposons DNA that moves around genome Telomeres Chromosome tips Centromeres Important for attachment to spindle Duplications Unknown Simple short repeats unknown

46 Transposons Mobile DNA elements
First identified in corn by Barbara McClintock in 1940s “selfish DNA”? Grouped by size and sequence similiarity: LINES long interspersed elements of 6,000 bases transcribed and trimmed to 900 bases SINES short interspersed elements of bases Alu element most common SINE in humans 300,000 to 500,000 copies => 2-3% of genome!

47 Gene expression changes during development

Download ppt "Gene Action and Expression"

Similar presentations

1 Gene expression Transcription and Translation 2 1.Important Features a. DNA contains genetic template for proteins. b. DNA is found in the nucleus.

1 Gene expression Transcription and Translation 2 1.Important Features a. DNA contains genetic template for proteins. b. DNA is found in the nucleus.
Gene Activity: How Genes Work

Gene Activity: How Genes Work
Central Dogma DNA is the genetic material within the nucleus.

Central Dogma DNA is the genetic material within the nucleus.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 3 Cell Structures and Their Functions Dividing Cells.

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 3 Cell Structures and Their Functions Dividing Cells.
Translation and Transcription

Translation and Transcription
1. Important Features a. DNA contains genetic template for proteins.

1. Important Features a. DNA contains genetic template" for proteins.
Protein Synthesis.

Protein Synthesis.
Genes and Protein Synthesis

Genes and Protein Synthesis
8.4 DNA Transcription 8.5 Translation

8.4 DNA Transcription 8.5 Translation
Protein Synthesis The genetic code – the sequence of nucleotides in DNA – is ultimately translated into the sequence of amino acids in proteins – gene.

Protein Synthesis The genetic code – the sequence of nucleotides in DNA – is ultimately translated into the sequence of amino acids in proteins – gene.
Genes as DNA: How Genes Encode Proteins

Genes as DNA: How Genes Encode Proteins
Transcription Transcription is the synthesis of mRNA from a section of DNA. Transcription of a gene starts from a region of DNA known as the promoter.

Transcription Transcription is the synthesis of mRNA from a section of DNA. Transcription of a gene starts from a region of DNA known as the promoter.
Quiz tiiiiime What 3 things make up a nucleotide?

Quiz tiiiiime What 3 things make up a nucleotide?
Bio 1010 Dr. Bonnie A. Bain. DNA Structure and Function Part 2.

Bio 1010 Dr. Bonnie A. Bain. DNA Structure and Function Part 2.
FROM DNA TO PROTEIN Transcription – Translation We will use:

FROM DNA TO PROTEIN Transcription – Translation We will use:
From DNA to Protein Chapter 14. 14.1 DNA, RNA, and Gene Expression  What is genetic information and how does a cell use it?

From DNA to Protein Chapter DNA, RNA, and Gene Expression  What is genetic information and how does a cell use it?
Protein Synthesis Transcription and Translation DNA Transcription RNA Translation Protein.

Protein Synthesis Transcription and Translation DNA Transcription RNA Translation Protein.
FROM DNA TO PROTEIN Transcription – Translation. I. Overview Although DNA and the genes on it are responsible for inheritance, the day to day operations.

FROM DNA TO PROTEIN Transcription – Translation. I. Overview Although DNA and the genes on it are responsible for inheritance, the day to day operations.
1 Gene expression Transcription and Translation. 2 1.Important Features: Eukaryotic cells a. DNA contains genetic template for proteins. b. DNA is found.

1 Gene expression Transcription and Translation. 2 1.Important Features: Eukaryotic cells a. DNA contains genetic template for proteins. b. DNA is found.
1 Genes and How They Work Chapter 15. 2 Outline Cells Use RNA to Make Protein Gene Expression Genetic Code Transcription Translation Spliced Genes – Introns.

1 Genes and How They Work Chapter Outline Cells Use RNA to Make Protein Gene Expression Genetic Code Transcription Translation Spliced Genes – Introns.

Similar presentations

Ads by Google