Glossary of Biochemistry, Human Genome

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69) In human cells you have about 30K genes (genome), ~150K mRNAs (transcriptome), ~1 million proteins (proteome), how can there be more mRNAs and proteins than genes?
Due to alternative splicing, and post-translational modifications.
70) 5% of DNA is?
Highly conserved.
71) 2% of DNA?
Actually codes.
72) 44% of DNA is?
73) 6% of DNA is?
74) 45% of DNA is?
Transposon repeats.
75) 93% of mitochondrial DNA is?
Highly conserved.
76) Why are exons conserved elements?
Gene sequences have different susceptibility to mutations, because mutations within some elements are less likely (they result in lethality). Therefore, the real important part of key genes must be highly conserved.
77) What are the top 5 protein domains in the human genome?
1)Zinc Finger (~29K copies); 2) Cadherin domain (~4K copies); 3) Epidermal growth factor domain (~3K copies); 4) Immunoglobulin domain (~2K copies); 5) Calcium-binding EF hand domain (~1,9K copies).
78) Whole genes are concerved and important genes are?
79) Gene length varies enormously, bigger genes have a greater susceptibility to?
80) Bigger genes have higher proportions of?
Non-coding sequence.
81) The biggest portion of the genome is unknown for what it codes for, however, out of the genes we know what their functions is, the greatest functional breakdown is for those genes involved in?
82) What are transposons?
Transposons (a.k.a. jumping genes) are sequences of DNA that can move around different positions within the genome of a single cell, in a process called Transposition. In the process, they can cause mutations and change the amount of DNA in the genome. Transposons are also called “jumping genes” or “mobile genetic elements”.
83) Of the 5% highly conserved DNA in the human genome, only about 40% of these genes are coding sequences. Why are other DNA sequences conserved?
Because, the genome also needs “handles” for its own organization (ex. DNA packing sequences, nucleosomes binding elements).
84) What makes up about half of the genome?
Repetitive non-coding elements (transposon repeats).
85) Heterochromatin is?
Permanently condensed, and transcriptionally inactive DNA.
86) Is the sequence of heterochromatin DNA determined?
87) Satellite DNA is comprised of?
Tandemly repeated sequence of 5-170 bp in length.
88) Were is the location of Satellite DNA?
89) Minisatellite DNA is comprised of?
Repeats of 9-64bp in length.
90) Were is the location of minisatellite DNA?
91) Microsatellite DNA is also called “simple sequence repeats”, what is it used for?
Identification of “bad” genes in pedigrees because it is highly variable in length between individuals.
92) If I have a free floating protein and free floating DNA in the same place, what would happen?
They would bind together.
93) What kind of bonds would they form?
Non-covalent, freely reversible.
94) Protein DNA-binding regulates the rates of?
Transcription, and replication.
95) Protein DNA binding is regulated by?
Protein concentration, and small molecule effectors (allosterism)
96) What part of the histone complex tethers DNA?
H1 protein “binder function”.
97) Name all of the histones in a histone complex?
H1 (1) binder function, H2A (2), H2B (2), H3 (2), H4 (2).
98) The core of the histone molecule is comprised of how many histones?
99) DNA that is ready to be transcribed is?
100) DNA that is transcriptionally inactive is?
Deacetylated (a.k.a. Methylated).
101) These changes to DNA regulate?
Transcription and replication rates.
102) In proteins what does the structure of Helix-Turn-Helix do?
In proteins, the helix-turn-helix (HTH) is a major structural motif capable of binding DNA. It is composed of two alpha helices joined by a short strand of amino acids and is found in many proteins that regulate gene expression.
103) What is retinoblastoma?
A rare form of cancer (a.k.a. Cat’s eye) caused by mutation of the RB1 gene. This gene encodes a protein important in the cell cycle.
104) In proteins what does the structure of Helix-Loop-Helix do?
H-L-H proteins readily form dimers and can “mix-and-match” to modulate transcription rates.
105) What syndrome is caused by a mutation in the TWIST gene, an H-L-H transcription factor?
Saethre-Chotzen Syndrome (acrocephalosyndactyly type III).
106) What DNA binding proteins are very important in steroid hormone signal transduction?
Zinc Fingers.
107) Zinc Fingers are very important in what type of hormone signal transduction?
Steroid hormone.
108) Name a few examples of human diseases caused by mutations in Zinc Finger transcription factors?
Inherited breast cancer, Wilms Tumor (accounts for 8% of childhood cancers), and Rickets.

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