module 3 (exam 2) Flashcards
what is a simplified version of the central dogma?
DNA (genes) —> mRNA—> proteins
genes are made of…
-DNA which stores information in code form
-info stored is used to make products preforming cellular functions
mRNA
temporary and portable version of information stored in a gene
-nucleotides A,C,G, and U connected together
DNA
permanent record or archive for information
-nucleotides A,C,G, and T connected together
alleles
different versions of the same gene
protein
-made of amino acids connected together
-carries out most of the work in cells
if new genes are introduced to an organism by humans…
the organism will make new proteins
what creates mutations in genes?
changes in DNA, leading to changes in mRNA and proteins
-changes result in dysfunctional proteins
transcription
-DNA to mRNA
-sequence of DNA bases in a gene acts as a template for the synthesis of an RNA molecule (RNA polymerase)
RNA polymerase
-molecular machine binds to DNA at the start of a gene
-catalyzes the formation of the phosphodiester bonds b/w ribonucleotides (RNA monomers) based on the sequence of A,C,G, and Ts in the gene
the newly made RNA strand forms…
-hydrogen bonds with one of the DNA strands in the gene
-has the same sequence as the DNA strand expect the the Ts are replaced with Us
translation
-MRNA to protein
-ribosome builds protein using the info from the mRNA made in transcription
tRNA
-transfer RNA
-20 types
-binds to different amino acid and transports it to the ribosome where the amino acid is incorporated into a growing protein during translation
rRNA
-ribosomal RNA
-component of the ribosome where protein synthesis during translation takes place
some RNA roles
-defending (from viruses or infections)
-regulation of which gene a cell expresses by speeding up or slowing down rate of transcription
-modifying mRNAs before mRNAs are translated
-catalyzing chemical reactions
DNA
deoxyribonucleic acid
RNA
ribonucleic acid
nucleic acid
made up of a string of nucleotides joined by covalent bonds
nucleotides
-subunits of amino acids
-made up of a phosphate group, 5 carbon sugar, and nitrogenous base
phosphate group
contains a phosphorus atom
sugar molecule
-O or H atoms bonded to form, C=O, C-OH, and C-H groups
nitrogenous base
contains carbon and nitrogen atoms bonded to form ring structures
phosphodiester bonds
connections b/w 2 nucleotides
monomer
small molecule that can be linked
polymer
monomers covalently bonded to form larger macromolecules
are nucleic acids polar or nonpolar
polar
5’ end of nucleic acids contain
phosphate group (PO4 3-)
3’ end of the nucleic acids contain
hydroxyl group (-OH)
you read primary structures from the
5’ to the 3’
DNA primary structure
-sequence of nucleotides in a nucleic acid
four different nucleotide bases
-Cytosine (C)
-Thymine (T)
-Guanine (G)
Adenine (A)
sugar-phosphate ack bone
sugar and phosphate bonds linked by phosphodiester bonds line up
DNA and RNA similarites
-both read from 5’ to 3’ polarity
- sugar-phosphate backbone
RNA differs from DNA b/c
-RNA doesn’t have thymine but uracil instead (U)
-ribonucleotides have 2 OH groups on the 2’
DNA secondary structure
-double helix
-aniparallel fashion (opposing 5’-3’ ends connect)
G-C and A-T are
DNA complementary pairs
RNA secondary structure
-stem and loop formation
-A-U and G-C are the complementary base pairs
key similarities of DNA and RNA
-primary structure made of sequence of nucleotides joined by phosphodiester bonds
-5’ to 3’ polarity and sugar-phosphate backbone
-forms secondary pairs consisting of double helix and aniparallel strands
Key DNA and RNA differences
-5-carbon sugar in RNA is ribose and its deoxyribose in DNA
-RNA has a OH group on is 2’ making it less stable and reactive
-DNA secondary structure is more stable
G and C pairs have ___ H-bonds
3
A and T pairs have ___ H-bonds
2
A and G are
purines (2 rings/larger rings)
C U and T are
pyrimidines (smaller rings)
gene
-has structural and regulatory sequences
-segments of a double helix that code for specific products
allele
-version of gene
-can be defined by any difference in structural or regulatory of a gene
DNA molecules are one long
double helix
chromosome are formed by
specialized proteins bind to the double helix
histones
-in eukaryotes
-proteins that bind to the DNA to form the chromosome
chromosomes in bacteria and archaea
circular
chromosomes in eukaryotes
linear
haploid number
the number of different types of chromosomes present in a cell, indicated by the number n
ploidy
the number of each type of chromosome present in a cell, written before the by number n
haploid (short def)
having one of each type of chromosome
diploid
having two of each type of chromosome
homologous chromosomes
different versions of the same chromosome type
replicated chromosome
a chromosome comprised of two identical DNA molecules joined together
sister chromatids
identical copies in a replicated chromosome
after DNA replication, a single chromosome consist of…
two identical copies of the same DNA molecule, complex with proteins that hold the two double-helices together
sister chromatids
two strands that make up a replicated chromosome, they are identical copies
non-sister chromatids
strands on homologous chromosomes and are different homologs not joined together
homologous chromosomes or homologs
different versions of the same chromosome
haploid saying
“the number is the number of different types of chromosomes in a cell”
ploidy saying
“the number of each type of chromosomes in a cell
transcription is a highly regulated process
-specific genes can be turned on or off and the production of RNAs from a particular gene can be sped up or slowed down
gene expression
refers to the entire set of processes that results in using the information stored in a gene
positive control
molecules or events that increase gene expression
negative control
molecules and events are decrease gene expression
in bacteria we can observe that structral sequences are found
-found together, along the chromosome
-transcription of this is under the control of the same set of regulatory sequences
operon
a group of genes with common function and under the control of common regulatory sequences
promoter
site where RNA polymerase makes initial contact with DNA to start transcription
-every operon has a promoter
-every gene not part of a operon has a promoter
regulatory proteins
transcription factors that regulate gene expression and bind to sequences in the DNA
activators are transcription factors that
help exert positive control
repressors are transcription factors that
help exert negative control (silence)
enhancers are regulatory sites in DNA that
are involved in positive control
silencers regulatory sites in DNA that
are involved in negative control
activeators bond to
enchancers
repressors bind to
silencers
similarities b/w bacterial and eukaryotic genes
-each gene has a promoter up stream, before the 5’ end, of the new RNA that will be made
-promoter is where RNA polymerase binds to DNA and begins transcription
-when transcription factors bind to a genes or operon regulatory sequences, they can enhance or repress transcription
exons
expressed
amino acids found in a protein product
introns
intervene b/w exons
get transcribed but are later removed from mRNA before translation
nucleosome
group of four histone proteins that has DNA wrapped around it
