Genetic information, variation and relationships between organisms (p1)

Question 1

RNA vs DNA

Answer 1

-RNA contains ribose DNA deoxyribose
-RNA contains uracil not thymine
–RNA is single stranded DNA double
-RNA strands are shorter

Question 2

structure of DNA

Answer 2

-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

Question 3

In prokaryotic cells, DNA molecules __________, circular and _____
associated with proteins

Answer 3

In prokaryotic cells, DNA molecules are short, circular and not
associated with proteins

Question 4

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 __________.

Answer 4

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.

Question 5

how is DNA stored in eukaryotic cells?

Answer 5

-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

Question 6

how is a chromosome formed in eukaryotic cells?

Answer 6

-long DNA double helix
-wound around histone proteins
-DNA with the proteins coiled repeatedly
-forming a single chromosome

Question 7

why is DNA wound around histones? (eukaryotic)as

Answer 7

-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

Question 8

________ 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.

Answer 8

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.

Question 9

Mitochondrial DNA

Answer 9

-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)

Question 10

chloroplasts DNA

Answer 10

-chloroplasts conatain single circular chromosome composed of DNA
-chloroplast DNA conrrains many genes necessary for proper chloroplast functioning

Question 11

How is DNA stored in prokaryotic cells?

Answer 11

-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

Question 12

how does DNA condense to fit in cell to fit in cell Prokaryotic

Answer 12

DNA double helix forms a cirular chromosome, which coilds and coils further to fit in cell (this is supercoiling).

Question 13

Eukaryotic vs prokaryotic packaging

Answer 13

-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)

Question 14

Eukaryotic vs prokaryotic quantity

Answer 14

-prokaryotic cells typically have 1 main chromosome,may have a few copies of it

Question 15

A ______ is a base sequence of DNA that codes for:
* the amino acid sequence of a ___________
* a functional RNA (including ribosomal RNA and tRNAs).

Answer 15

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).

Question 16

Gene

Answer 16

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.

Question 17

A gene occupies a fixed position, called a _________, on a particular
DNA molecule.

Answer 17

A gene occupies a fixed position, called a locus, on a particular
DNA molecule.

Question 18

what determine the order of amino acids in a ploypeptide

Answer 18

the order of bases in a gene, each amino acid is coded for by a sequence of 3 bases called a triplet

Question 19

genome

Answer 19

complete set of genes in a cell

Question 20

proteome

Answer 20

the full range of proteins a cell is able to produce

Question 21

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.

Answer 21

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.

Question 22

introns

Answer 22

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.

Question 23

exons

Answer 23

coding areas,all the areas that do code for an amino acid

Question 24

regions of mutiple repeats in eukaryotes

Answer 24

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.

Question 25

allele

Answer 25

different versions/forms of the same gene

Question 26

the order of ______________ in each allele is slightly different so they code for slightly different versions of the same _____________.

Answer 26

the order of bases in each allele is slightly different so they code for slightly different versions of the same polypeptide.

Question 27

homologous pairs

Answer 27

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

Question 28

locus

Answer 28

the fixed posisition alleles of the same gene are on each chromosome of a homologous pair.

Question 29

________________ 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.

Answer 29

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.

Question 30

protein synthesis

Answer 30

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.

Question 31

mRNA

Answer 31

-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

Question 32

tRNA

Answer 32

-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

Question 33

transcription

Answer 33

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

Question 34

antisense strand

Answer 34

the template strand, mRNA produced is complementary to this strand

Question 35

Translation

Answer 35

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

Question 36

sense strand

Answer 36

the coding strand, has the same code as mRNA produced

Question 37

protein synthesis is euakryotes vs prokaryotes

Answer 37

-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)

Question 38

A sequence of three DNA bases, called a __________, codes for a specific amino acid. The genetic code is universal, non-overlapping and _________

Answer 38

A sequence of three DNA bases, called a triplet, codes for a specific amino acid. The genetic code is universal, non-overlapping and degenerate

Question 39

splicing

Answer 39

in eukaryotes introns and exons are both copied into mRNA. mRNA containing introns and exons is called pre-mRNA . A process called splicing removes the introns and joins the exons together. Forming mature mRNA. this occurs in the nucleus.

Question 40

genetic code

Answer 40

sequence of base triplets in mRNA that code for a specific amino acid. each base triplet is read in sequence separate from the triplet before and after it. base triplets don't share their bases because code is non overlapping

Question 41

genetic code is non-overlapping

Answer 41

each base only forms part of one triplet

Question 42

genetic code is degenerate

Answer 42

each amino acid is coded for by more than one triplet

Question 43

genetic code is universal

Answer 43

the same specific base triplet codes for the same amino acid in all living things