Genetic information, variation and relationships between organisms (p1) Flashcards
paper 1 (and 3)
RNA vs DNA
-RNA contains ribose DNA deoxyribose
-RNA contains uracil not thymine
–RNA is single stranded DNA double
-RNA strands are shorter
structure of DNA
-double helix
-2 strands, polynucleotides
-nucleotides made from phosphate group, ribose sugar and nitrogen containing organic base (A,T,C orG.)(between phosphate and sugar = ester bond and between base and sugar=glycosidic)
-sugar phosphate back bone=phosphodiester bond between phosphate molecule of one and sugar of another
-hydrogen bonds between strands
In prokaryotic cells, DNA molecules __________, circular and _____
associated with proteins
In prokaryotic cells, DNA molecules are short, circular and not
associated with proteins
In the nucleus of eukaryotic cells, DNA molecules are very ____,
linear and associated with proteins, called ______. Together a
DNA molecule and its associated proteins form a __________.
In the nucleus of eukaryotic cells, DNA molecules are very long,
linear and associated with proteins, called histones. Together a
DNA molecule and its associated proteins form a chromosome.
how is DNA stored in eukaryotic cells?
-contain long linear DNA molecules that exists as chromosomes-made of the DNA molecule and associated ptoteins
-chromosomes are in the nucleus
-the DNA molecule is very long so wound up to fit in nucleus,wound around histones-they also help support the DNA , the DNA is coiled up very tight to form a chromosome
how is a chromosome formed in eukaryotic cells?
-long DNA double helix
-wound around histone proteins
-DNA with the proteins coiled repeatedly
-forming a single chromosome
why is DNA wound around histones? (eukaryotic)as
-DNA is very long so has to be wound up to fit in the nucleus
-wound around histones, thes also support DNA
-The DNA and proteins coiled very tightly to form a compact chromosome
________ and ______ also have their own DNA , It is similar to _________ DNA because it is circular and shorter than DNA found in to nucleus. It is ______ associated with proteins.
mitochondria and chloroplast also have their own DNA , It is simular to prokaryotic DNA because it is circular and shorter than DNA found in to nucleus. It is not associated with proteins.
Mitochondrial DNA
-in humans spans about 16,500 base pairs ,represnting a small fraction of total DNA in cells
-contains 37 genese,all essential for normal mitochondrial function
-13 of these genes provide instructions for making enzymes involved in oxidative phosphorylation (used to create ATP)
chloroplasts DNA
-chloroplasts conatain single circular chromosome composed of DNA
-chloroplast DNA conrrains many genes necessary for proper chloroplast functioning
How is DNA stored in prokaryotic cells?
-also carry DNA as chromosomes
-but DNA molecules are shorter and circular
-it isnt associated with histones-it condenses to fit in cell by supercoiling
how does DNA condense to fit in cell to fit in cell Prokaryotic
DNA double helix forms a cirular chromosome, which coilds and coils further to fit in cell (this is supercoiling).
Eukaryotic vs prokaryotic packaging
-prokaryotes and eukaryotes package molecules in prtein structures called chromosomes
-prokaryotic chromoes are cirular and reside in cell region called the nucleoid (chromosmes in nucleus eukaryotic)
Eukaryotic vs prokaryotic quantity
-prokaryotic cells typically have 1 main chromosome,may have a dew copies of it
A ______ is a base sequence of DNA that codes for:
* the amino acid sequence of a ___________
* a functional RNA (including ribosomal RNA and tRNAs).
A gene is a base sequence of DNA that codes for:
* the amino acid sequence of a polypeptide
* a functional RNA (including ribosomal RNA and tRNAs).
Gene
sequence of DNA bases that code for either functional RNA or an amino acid . The sequence of amino acids in a polypetide for the primary structure.
A gene occupies a fixed position, called a _________, on a particular
DNA molecule.
A gene occupies a fixed position, called a locus, on a particular
DNA molecule.
what determine the order of amino acids in a ploypeptide
the order of bases in a gene, each amino acid is coded for by a sequence of 3 bases called a codon
genome
complete set of genes in a cell
proteome
the full range of proteins a cell is able to produce
Genes that don’t code for an amino acid code for ___________ RNA instead, ___________RNA is RNA other than mRNA which perform special tasks during _________ synthesis e.g tRNA and ribosomal RNA, which forms part of the Ribosome.
Genes that don’t code for an amino acid code for functional RNA instead, functional RNA is RNA other than mRNA which perform special tasks during protein synthesis e.g tRNA and ribosomal RNA, which forms part of the Ribosome.
introns
non coding areas, secontions of genes that do not code for amino acids, there can be several introns within a gene . in eukaryotes introns are removed in protein sythesis- so they don’t affect the amino acid order. prokaryotes don’t have introns.
exons
coding areas,all the areas that do code for an amino acid
regions of mutiple repeats in eukaryotes
eukaryotes contain areas of multiple repeatsoutside of genes. DNA sequence that repeats over and over. these areas don’t code for amino acids so called non-coding mutiple repeats.
allele
different versions/forms of the same gene
the order of ______________ in each allele is slightly different so they code for slightly different versions of the same _____________.
the order of bases in each allele is slightly different so they code for slightly different versions of the same polypeptide.
homologous pairs
pairs of matching chromosomes,in homologous pairs both chromosomes are the same size and have the same genes although they may have different alleles.allelles coding for the same gene will be found at the same fixed posistion (locus) on each chromosome in the pair
locus
the fixed posisition alleles of the same gene are on each chromosome of a homologous pair.
genome
full set of genes in a cell
proteome
the full range of proteins a cell is able to produce
________________ as the production of mRNA from DNA. The role of
RNA polymerase in joining mRNA _____________
* In prokaryotes, transcription results directly in the production
of mRNA from DNA.
* In eukaryotes, transcription results in the production of premRNA; this is then ______ to form mRNA.
_________ as the production of polypeptides from the sequence of
codons carried by mRNA. The roles of ribosomes, tRNA and ATP.
Transcription as the production of mRNA from DNA. The role of
RNA polymerase in joining mRNA nucleotides.
* In prokaryotes, transcription results directly in the production
of mRNA from DNA.
* In eukaryotes, transcription results in the production of premRNA; this is then spliced to form mRNA.
Translation as the production of polypeptides from the sequence of
codons carried by mRNA. The roles of ribosomes, tRNA and ATP.
protein synthesis
the production of proteins from information contained in cells DNA. Occurs in 2 stages transcription (DNA code copied into an mRNA molecule) Translation (mRNA molecule joins to a ribosome and the code it carries is used to sythesie a protein.
mRNA
-made during transcription
-carriers genetic code from the DNA tp the ribosome where it is used in translation to sythesise a protein
-is a single polynucletide strand
-groups of 2 adjacent bases are codons
tRNA
-invloved in translation
-carries amino acids used to make proteins to the ribosomes
-single polynuceltide strand folded into a clover shape.
-each tRNA molecule has a specific sequence of 3 bases on one end called an anticodon
-has a amino acid bidning site at the other end
transcription
1.RNA polymerase atathces to DNAat the beginning of a
gene. in euakaryotes hydrogen bonds between the 2 strands are broken by DNA helicase attached to RNA polymerase separating the strands allowing DNA to uncoil and some bases to be exposed . one strand is use as a template to make a mRNA copy
2.complemtary mRNA is formed-RNA polymerase lines up free RNA nucleotide alongside the exposed bases of the template strand. free basis are attarcted to the exposed bases. complemnaty base paring means the mRNA strand ends up being a complemntary copy of the template DNA strand . once RNA nucleotides have paired up with the specific bases of the DNA strand they are joined together by RNA polymerase formign mRNA.
3.RNA polymerase moves down the DNA strand- moves along DNA strand assembling the mRNA strand.hydrogen boinds of uncoiled DNA reform when RNA polymerase has passed by amd starnds coil back into a double helix
4.RNA polymerase reaches a stop signal-when it reaches a particular sequence (stop signal) it stops producing mRNA and detaches from DNA .
In euakaryotes mRNA movesout the nucleus through a nucleur pore and attahces to a ribosome in the cytoplasm where translation takes place
antisense strand
the template strand, mRNA produced is complementary to this strand
Translation
second stage of protein synthesis, occurs in cytoplasm at ribosomes. amino acids are joined together to form a polypeptide chain following the sequence of codons carried by the mRNA.
1.mRNA attaches it self to a ribosome and tRNA molecules carry amino acids to it. ATP provide energy needed for bond bwteen tRNA molecule and amino acid to form
2.tRNA with an anticodon complemenatry to the first mRNA codon attaches to mRNA strand by complementary base pairing. the second tRNA attaches itself to second mRNA coding in same way.
3.two amino acids attached to the tRNA molecules are joined by a peptide bond. the first tRNA molecule movs away leaving its amino acid behind
4.3rd tRNA moleclle bind to next codon , its amino acid bind to the fist two and the 2nd amino acid moves away, process continues forming a polypeptide chainuntil theres a stop signal on the mRNA molecule
5.polypeptide chain moves away from ribosome
sense strand
the coding strand, has the same code as mRNA produced
protein synthesis is euakryotes vs prokaryotes
-mRNA in euakryotes has to be spliced to remove introns
-translation occurs in cytoplasm of euakryotes and trancription in the nucleus
-prokaryotes transcription and translation occurs in cytoplasm (possibly at the same time)
