39182062
Description
Flashcards by Abigail Leslie, updated more than 1 year ago
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Created by Abigail Leslie
about 1 year ago
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| Question | Answer |
| Transcription Regulation | Key to all cell diversity, same genome codes for every cell, regardless of type. |
| Housekeeping genes | Genes expressed in all cells regardless of type - Ribosomal, metabolic enzymes, structural proteins |
| Unique or differentiation specific genes | Define the function of the cell - hemoglobin, growth hormone, factor VII |
| Chromatin | The complex of chromosomal proteins with the nuclear DNA of eukaryotic cells. Makes up chromosomes Mass of proteins = Mass of DNA |
| Chromosomes | DNA and packing proteins that condense, protect, and regulate DNA. |
| Euchromatin | Less condensed chromatin that is being actively transcribed |
| Heterochromatin | More condensed chromatin, not actively being transcribed |
| First DNA packing stage | Histone binding is? |
| Histones | Small, positively charged proteins that bind to DNA. (Many basic binding proteins) |
| Nucelosome | The DNA-Histone complex is called: |
| H2A - H2B - H3 - H4 | The four main sub units of histones: |
| H3-H4 Heterotetramer | This histone tetramer associates with DNA (dimer of dimers) |
| H2A-H2B Dimer | Two of these dimers associate with the H3 - H4 Heterotetramer to form an octamer |
| H1 | This histone subunit (outside of the main four) locks the histone-dna complex |
| Beads on a string | The structure of histone-bound DNA is often described as: |
| Histone Core | Nucelosomes contain ~146 bp of DNA wrapped around this section of the Histone: |
| Histone Tail | This section of a Histone has an undefined structures, but modification to it are important for regulation and function. They also interact with themselves on other Histones: |
| 30 nm fiber | Regular arrangement of nucleosomes that bring the molecules together |
| False | True/False: Histone binding is sensitive to DNA sequence |
| True (Nucleosome formation is preferential at certain DNA sequences) | True/False: Nucleosome formation is sensitive to DNA sequence |
| Nuclesome Formation | A-T rich regions and Pyrimidine Purine sequences (TpA, CpG) are more preferential to: |
| Heterochromatin | Repetitive DNA sequences, Ribosomal RNA synthesis genes and telomeres are more likely to be: |
| Histone Acetylation | This Histone modification is the most common. Occurs on Lysine (H3 and H4 mostly), and is associated with active transcription |
| HATs (Histone Acetyltransferases) | This class of enzyme causes Lysine side chains on Histones to become acetylated |
| HDACs (Histone Deacetylases) | This class of enzyme causes Lysine chains on Histones to become deacetylated |
| Methylation of H3 Lysine 9 | This Histone modification is associated with repression of transcription when occuring on this side chain |
| Methylation of H3 Lysine 4 | This Histone modification is associated with active transcription when occuring on this side chain |
| Histone Methylation | This Histone modification is associated with repression or activation, depending on the residue it occurs on |
| Chromodomains | Proteins that bind to specific methylated lysines, often associated with transcriptional silencing |
| Histone code | The idea that the modifications to histones are associated with how actively it is transcribed and that histone modifications are not independent and worked together is called: |
| Histone Phosphorylation | This histone modification is associated with additional regulatory signals. When occuring on H3 Serine 10 it is associated with cell growth. When occuring on H3 Serine 10 and Serine 28, it is associated with chromosome condensation |
| Histone Ubiquitination | This histone modification occurs on Lysine side chains. Is associated with transcription regulation, DNA repair, and histone proteolysis |
| Chromatin Remodeling Complexes | These enzymes increase accessibility of DNA by : 1. Sliding the histone octamer along DNA 2. Removing the histone octamer 3. Changing the histone octamer 4. Introducing transient loops into the DNA wrapped around a histone core |
| • ATPase domain (universal) • Bromodomain (binds acetylated lysines) • Chromodomain (binds methylated lysines) • SANT-SLIDE (binds histone tails) | These are the domains of Chromatin Remodeling Complexes: • One is universal • One binds acetylated lysines • One binds methylated lysines • One binds histone tails |
| One Model: CRC creates a distortion around the histone octamer, which results in sliding of octamer to a new position on the DNA | How does Chromatin Remodeling Complexes work? |
| Direct DNA modification | Methylation of DNA is an example of what? |
| DNA methyltransferase | This enzyme makes 5-methyl cytosine on DNA |
| Methylated cytosines are more likely to undergo spontaneous deamination | Why is DNA methylation risky? |
| 5-M cytosine will deaminate into Tyrosine | Why is 5-methyl cytosine deamination worse than cytosine deamination? |
| DNA methylation | This DNA modification silences transcription in Eukaryotes, and can be inherited |
| X-chromosome inactivation | This is an example of chromasomal silencing |
| In females, one X chromosomes is deactivated. An effect of this occurs in cats, where coloring is connected to the X chromosome. Depending on the X gene deactivated, causes different patches of colored fur. | What is X-chromosome inactivation? |
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