DNA: the code of life Flashcards
nucleic acid
a type of organic compound
DNA and RNA are examples of nucleic acids found in the nucleus
a macromolecule (made from monomers, building blocks called nucleotides) AKA polymer
monomer
a building block
nucleotide
the monomer of nucleic acid, which forms DNA and RNA
DNA
deoxyribonucleic acid is made up of nucleotides
nitrogenous bases adenine, thymine, guanine and
cytosine ( g cat)
carries the genetic code for protein synthesis
-type of nucleic acid
nuclear DNA
DNA found in the nucleus
extra- nuclear DNA
DNA found outside of the nucleus: mitochondrial and
chloroplastic DNA.
double helix
the shape of DNA consists of two strands joined together
and twisted spirally
hereditary
genetic information passed on from parent to offspring
main functions of DNA (3)
1) Controls the functioning of cells
2) Regulate the functioning of genes
3) Passes on hereditary characteristics
RNA
Type of nucleic acid
-RNA consists of nucleotides. Nitrogenous bases found in
RNA are adenine, uracil, guanine and cytosine
messenger RNA (structure, formed location, function)
structure: single strand with unlimited number of nucleotides
formed location: in nucleoplasm, by complementary nucleotides on DNA template
function: carries genetic code from DNA in nucleus
- acts as messenger
ribosomal RNA (structure, function)
structure: single strand (remember: its RNA so single stranded)
function: forms part of ribosome structure in cytoplasm
+ plays role in control of protein synthesis
transfer RNA (structure, location, function)
structure: single strand folded back on itself like a hairpin (remember: its RNA so single stranded)
location: in cytoplasm
function: picks up amino acids in cytoplasm according to coding of according to coding of codon (of mRNA) and takes them to the ribosomes for protein synthesis
- acts as transfer molecule
what are the three types of RNA (ribonucleic acid)
1) messenger RNA (mRNA)
2) ribosomal RNA (rRNA)
3) transfer RNA (tRNA)
where is RNA formed and by what
all formed in the nucleus by DNA.
name where the 3 diff RNA can be found
1) Messenger RNA (mRNA) is formed in the nucleus but then enters the
cytoplasm where it attaches to ribosomes.
2) Ribosomal RNA (rRNA) is found in the ribosomes in the cytoplasm of the
cell.
3) Transfer RNA (tRNA) is found freely in the cytoplasm of the cell.
what is the role of RNA
The three types of RNA are very important to the process of protein synthesis, with
each type playing a unique role.
how are DNA and RNA similar (3)
they both:
1) contain sugar alternating with phosphate (pentose sugar)
2) contain the nitrogenous bases adenine, guanine and cytosine
3) play a role in protein synthesis
how is DNA diff from RNA (4)
DNA:
1)contains deoxyribose sugar
2) double helix and coiled
3) contains the nitrogenous base thymine
4) found in the nucleus only
how is RNA diff from DNA
RNA:
1) contains ribose sugar
2)single-stranded
3) contains the nitrogenous base uracil
4)found in the nucleus, ribosomes and
cytoplasm of cells
describe the DNA replication process
- The DNA double helix unwinds (due to enzymes running down the strand, enzyme name “gyrase”, donut shaped)
- The weak hydrogen bonds between the
nitrogenous bases are broken. The DNA
strands separate (they unzip)(due to another family of enzymes called “helicase”, unzips by breaking the hydrogen bonds) - Each original DNA strand
serves as a template on which its
complement is built - Free floating nucleotides build a DNA strand onto
each of the original DNA strands, attaching
their complementary nitrogenous bases
(A to T and C to G) - This results in two identical DNA molecules. Each molecule consists of one
original strand and one new strand
what is the importance of DNA replication
bef cell division (mitosis) , makes extra copy of each chromosome so that the 2 daughter cells produced have their own chromosomes
the gentic info present in the 2 daughter cells is the same as the mother cell
genes
stretch of DNA, can be any lengths depending on how much info they have
each gene has the coding for one polypeptide
non coding DNA
spaces betw genes
dont code for the making of polypeptide
regulates the expression of gene
what are the complementary DNA nitrogenous base
guanine- cytosine
adenine - thymine
what is the name of the pentose sugar in DNA
Deoxyribose (hint: from DNAs name )
why is DNA a polymer
it is made of Monomers called Nucleotides
central dogma of RNA and protein synthesis
DNA makes RNA and RNA makes proteins
DNA-> RNA -> Protein
recipe ->baker-> cake
from recipe bk
what are the 2 stages in which protein synthesis occur
Stage 1: Transcription
Stage 2: Translation
describe transcription stage in protein synthesis
1= A section of the DNA double helix unwinds. As a result,
-the weak hydrogen bonds between the nitrogenous bases of DNA break
- the DNA unzips (in this particular section of the DNA)
NOTE: “polymerase” controls the transfer of code from DNA to RNA.
2= One strand acts as a template
3= This DNA template is used to form a complementary strand of messenger
RNA (mRNA)
- This is done using free RNA nucleotides in the nucleoplasm
- The mRNA now contains the code for the protein which will be formed
- Three adjacent nitrogenous bases on the mRNA are known as codons.
These code for a particular amino acid.
4= mRNA moves out of the nucleus through a nuclear pore into the cytoplasm,
where it attaches onto a ribosome
desc the translation stage in protein synthesis
(5)
1- single mRNA strand formed in nucleus attaches to ribosome ( site for protein synthesis)
2- in ribosome: mRNA provide code for seq of amino acids (to form a specific protein (amino acid attached to tRNA)
3- tRNA picks up amino acid from amino acid pool in cytoplasm.
each tRNA carries specific amino acid.
(amino acid coded for by codons on mRNA, the tRNA anticodons also depend on codons on mRNA, anticodons are complementary to the codons)
4- amino acids join in sequence , this sequence det by mRNA codons.
-> peptide bonds form betw 2 adjacent amino acids (this forms a dipeptide)
-> more than 2 amino acids joined by peptide bonds (this forms a polypeptide chain)
5- after peptide bonds form . tRNA brks its bond with its amino acid (tRNA can now pick up another amino acid of same type
- process continues till 50+ amino acids join = protein forms
mutation
A mutation is a change in the nitrogenous base sequence of a DNA molecule
(or a gene)
amino acids
monomers of proteins
base triplet
three consecutive nitrogenous bases on DNA
transcription
1
st stage of protein synthesis – mRNA formed from DNA
carrying code for the protein to be made
translation
2nd stage of protein synthesis – amino acids combine to form
a protein
codon
three consecutive nitrogenous bases on mRNA –
these are complementary to the triplet on DNA
anti-codon
three consecutive nitrogenous bases on tRNA – these
are complementary to the codon on mRNA
name 7 DNA profiling / fingerprinting uses
1- identify crime suspects in forensic investigations (both samples, one from crime scene,looks exactly the same )
2- identify dead bodies (from DNA bank government has)
3- identify relatives
4- as proof of paternity ( child DNA combo of mother + father )
5- to determine probability and/ or causes of genetic defects
6- to trace missing people
7- to establish compatibility to tissue types for organ transplants
organic molecules that control the synthesis of proteins in all living cells by storing and transferring genetic info
nucleic acid (RNA)
DNA that occurs outside the nucleus
extranuclear DNA
long, thin thread - like structures that consists of DNA coiled around proteins called histones
chromosomes
a segment of a dna molecule that codes for a specific protein that controls a heritable characteristic and determines the appearance and functioning of an organism
gene
the three scientists that received the Nobel Prize for physiology/medicine in 1962 for the discovery of structure of DNA
1- James watson
2- Francis crick
3- Maurice wilkins
monomer of a nucleic acid composed of sugar, phosphate and a nitrogenous base
nucleotide
sugar molecule found in a nucleotide of dna
deoxyribose
the large nitrogenous base molecules, adenine and guanine
purine
the smaller nitrogenous bases, cytosine and thymine
pyrimidine bases
the code provided by the base sequence of DNA that gives the instructions for protein synthesis
genetic code
the dna that does not carry genetic info to produce proteins
non coding dna
the process by which dna duplicates to form 2 identical copies
replication
the 2 identical units of a chromosome after replication
chromatids
the structure that holds 2 chromatids together
centromere
the 1st step in the extraction of DNA where cells are broken down mechanically and/or chemically
lysis
the last step in the extraction of DNA during which the DNA becomes visible because it is insoluble in alcohol
precipitation / condensation
the barcode pattern formed by the base sequence of prepared processed DNA
dna profile / dna fingerprint
sugar molecule found in a nucleotide of RNA
ribose
the nitrogenous base that replaces thymine in rna
uracil
the type of RNA that caries the genetic code from the DNA in the nucleus to the ribosomes in the cytoplasm
mRNA
the type of RNA that picks up specific amino acids in the cytoplasm during protein synthesis and carries them to the ribosomes
tRNA
the type of RNA that forms part of the structure of the ribosomes in the cytoplasm and plays a role in the control of protein synthesis
rRNA
3 consecutive nitrogenous bases on a DNA strand that provides the code for a particular amino acid
base triplets
the process during which mRNA obtains the code for protein synthesis from DNA
transcription
the enzyme that controls the transfer of the code from the DNA to RNA and brks the weak hydrogen bonds betw the base pairs
RNA- polymerase
each grp of 3 consecutive bases on mRNA strand that codes for a particular amino acid
codon
3 exposed nitrogenous bases on a folded loop of each tRNA molecule
anticodon
the conversion of the code locked in the mRNA strand, to a particular amino acid sequence to build a specific protein
translation
dna profile/ fingerprint
descr of a persons genotype fro his/her unique DNA base pair seq, which is shown as a barcode pattern
forensic evidence
when biological specimans, eg, skin, blood, saliva, hair or semen are collected from a crime scene and the DNA is used as evidence In a court of law
forensic pathologist
the person who performs DNA tests on biological evidence found at crime scenes
