Overview of genetics Flashcards
mammalian cell structure organelles
1) plasmatic membrane
- smooth: only RBC
- all other cells have extensions on membrane (increase SA)
2) nucleus
- contains porous membrane
3) rough ER
- rough bc of ribosomes
- proteins are synthesized
4) golgi complex
- prepare proteins from ER for secretion
5) mitochondria
- energy factory
6) lysozome
- for digestion of endocytosed materials
7) centriole
- for mitosis
8) microfibrils and filaments
chromosomes and mitochondria DNA
1) 23 pairs, 22 are identical autosomes
- one pair of sex chromosomes
2) all the genomic dna is the same in all the cells in the body (zygote is precursor)
3) why do cells differ?
- because only some genes are expressed
4) mitochondria have own DNA
- circular like bacterial plasmid
- theory that some bacteria fused with archaea
DNA structure
1) sugar phosphate backbone: deoxyribose
2) nucleotide
- adenine, thymine, guanine, cytosine
3) structure is double helix
RNA structure
1) sugar phosphate backbone: ribose
2) nucleotides: uracil in place of thymine
3) single helix
chomosome
1) nucleosomes
- DNA double helix coiled around a histone protein (6 ft to several microns)
2) chromatin fibers
- coiled nucleosomes
3) chromosomes
- loops of chromatin fibers attaches to scaffold of nonhistone acidic proteins
*this is for size and space, and regulations of transcription
local uncoiling
1) DNA replication (but DNA pol)
2) RNA transcription (but RNA pol)
gene expression
1) transcription and translation
1) DNA: nucleotide sequence
2) mRNA: exact transcription
- DNA to RNA
3) mRNA is processed and spliced
- removes introns
- splice variants: in some cases specific exons are cleaved off
4) mRNA is translated into AA
5) active protein posttranslational modification often required
regulation of transcription
1) gene expression into protein is primarily controlled by transcriptional regulation
2) promotor
- sites in DNA, upstream from genes
- TFs bind to them
- once bound to the DNA, TFs recruit RNA pol
- GC box, TATA box, translation
enhancer-promoter interaction
1) promotor activated by TFs, on the same DNA strand
2) enhancer may be on different strand
- control transcription of genes in different cells
3) it is connected by DNA loop
- peptides keep loop together
- many Tfs and mediator proteins between enhancer and promoter
- if everything is there, the DNA sequence will be transcribed
epigenetics
1) noncoding RNAs
- affect gene transcription
- mRNA splicing
- translation
2) environmental factors affect gene expression
translation stage
1) process of converting mRNA into AA sequence
2) tRNA is anti-codon
- recognize mRNA and transport AA
3) post-translational modification
- 3D folding required for many proteins to function
new protein
1) assembly on ribosome
2) extrusion into ER
- helps folding of proteins
3) posttranslational modification and 3D folding
DNA mutations
1) substitution
2) deletion
3) insertion
—
1) silent
- doesnt alter the AA
2) nonsense
- insertion of a stop codon
3) missense
- different AA
4) frameshift
- insertions or deletions not in multiples of 3 consecutive nucleotides
single nucleotide polymorphism
1) most frequent structure mutations of DNA
2) one pair is exchanged
3) proteins function will be altered if AA is changed
4) can be silent, missense, or nonsense mutation
- many SNPs are in introns
5) there have been described several millions of SNPs in a human genome
insertion of nucleotide repeats
1) 3,4,5,12 nucleotides
2) total insertion may be 10,100s,1000s of repeats
3) exon, promoter region, intron
4)exon affect AA sequence directly
5) intron affect length of resulting protein due to abnormal splicing
—
can be tested and diagnosed in patient
