3.3 RNA Versus DNA Flashcards
Essential functions of RNA
- converts genetic code from DNA to proteins
- regulates the process of gene expression
- facilitates biological reactions
- senses and communicates responses to cellular signals
- exists as the genetic material found in some viruses
5’ end
Beginning end of nucleic acid where phosphate group is found
3’ end
Terminal end of a nucleic acid where a hydroxyl group is found
Antisense strand
Strand of DNA that produces RNA
Sense (coding) strand
Strand of DNA that will match with RNA, replacing U for T
Time of mRNA degradation
After translation
Structure of typical human protein coding mRNA
From 5’ to 3’
- cap
- 5’ UTR (untranslated region)
- start codon
- coding sequence
- stop codon
- 3’ UTR
- poly-a tail
Polyadenylated tail
Poly-a tail
About 200 adenine residues added to mRNA at end of transcription to prevent the enzymes in the cytoplasm from degrading the mRNA
tRNA
Gathers appropriate amino acids from the cytoplasm and delivers them to the ribosome.
rRNA
Part of the ribosome mechanism that assembles the amino acids according to the mRNA sequence
Frameshift mutations
Resulting from poorly defined start and stop locations during translations
Tay-Sachs disease
Sometimes caused by frameshift mutations which lead to absence of hexosaminidase A enzyme. Causes a buildup of waste in nerve cells leading to nerve damage and eventually death.
snRNA
Small nuclear RNA
Localized to the nucleus and involved in the splicing and processing of mRNA
scRNA
Small cytoplasmic RNA
Present in the cytoplasm
miRNA
Micro RNA
Small, highly conserved segments of non-coding RNA involved in. the regulation of gene expression
siRNA
Regulates gene expression through RNA interference
Can be commercially synthesized
RNAi
RNA interference
Silences genes by specifically targeting and degrading their mRNA
Retrovirus
Has RNA as its genetic material. Uses reverse tanscriptase to covert RNA into DNA and integrates it into host DNA in order to replicate
Four crucial steps for cells of a multicellular organism
- Cell proliferation
- Cell specialization and differentiation
- Cell-cell interactions
- Cell movement
How long does a zygote stay single-celled?
12 hours
How many cells are in a 3 day old zygote?
16 cells
Amount of cells in an average human adult
About 3 trillion
Proliferation
Create exact copies of a given cell
Protein p53
Binds DNA to inhibit the development of and growth of tumors
- Can stimulate DNA repair
- stop cell w/ DNA damage from proceeding through cell cycle
- initiate apoptosis
p53 mutation
Found in 50% of cancers
Can be inherited
iPSC
Induced pluripotent stem cells
Reprogrammed adult cells that have been reprogrammed to be pluripotent
May have DNA abnormalities that develop from a lifetime of cell division
Direct contact interactions
Connected cells with channels between them allow chemicals to diffuse between them
Paracrine
Chemical signal diffuses out of one cell and reaches nearby cells
Synaptic signaling
Specific type of paracrine signaling in the nervous system
Occurs between cells separated by a synapse
Neurotransmitters diffuse from one cell to another
Autocrine signaling
Cell signals to itself by releasing chemicals that bind to receptors on the outside of the cell
T-lymphocytes
Produce cytokine proteins that bind to the outside of the same cells to stimulate their own proliferation in order to initiate an immune repose
Endocrine signaling
Signaling conducted by hormones that can travel throughout the body via the circulatory system
