9. NUCLEUS Flashcards
What is dna and its role?
. DNA is the information molecule.
It stores instructions for making other large molecules, called proteins.
These instructions are stored inside each of your cells, distributed among 46 long structures called chromosomes.
These chromosomes are made up of thousands of shorter segments of DNA, called genes.
What crucial characteristics must a molecule exhibit to serve as the genetic material
replication, storage of information, expression of information, and variation by mutation.
Describe replication
‘the process by which the genome’s DNA is copied in cells. Before a cell divides, it must first copy (or replicate) its entire genome so that each resulting daughter cell ends up with its own complete genome.
Describe storage of information
Storage of information requires the molecule to act as a repository of genetic information that may or may not be expressed by the cell in which it resides.
Ie- skin cells synthesis melanin but not hemoglobin
Define the genetic material
Is the source of variability among organisms, through the process of mutation
Define mutation
A change in the chemical composition of DNA
What is the affect of mutation on genetic material ?
the alteration is reflected during transcription and translation, affecting the specific protein. If a mutation is present in a gamete, it may be passed to future generations and, with time, become distributed in the population.
What is genetic variation ?
the presence of differences in sequences of genes between individual organisms of a species. It enables natural selection, one of the primary forces driving the evolution of life
Describe the molecular structure of dna
Is a polymer- large molecule built up by repeatedly linking together small molecules- monomers
Dna monomers- nucleotides
What is the organisation of the human genome?
Double-stranded chain of deoxyribonucleotides in cells
Both strands are complementary to each other and run antiparallel.
Nucleotides form single-stranded DNA that stabilizes into double-stranded DNA
DNA conforms into right-handed double helix that binds histone octamers to form nucleosomes (appear as “beads on a string” under electron microscopy)
Chromatin formation begins, which is then further compacted
During replication (mitosis or meiosis), chromatin maximally condenses into chromosomes (only visible during metaphase under light microscopy)
Describe the double helix
3D structure of DNA in which two polynucleotide strands are intertwined, stabilized by:
Specific base pairing via hydrogen bonds (H bonds) between complementary nucleobases of DNA
A-T bonds consist of 2 H bonds
G-C bonds consist of 3 H bonds, resulting in a stronger bond (an ↑ in G and C in DNA → ↑ melting temperature of DNA)
What is the hydrophobic effect?
The negatively charged sugar-phosphate backbone is located on the outside of the helix, the bases on the inside.
What is the function of nuclei acids
function primarily in the storage and transmission of genetic information, but they may also have structural or catalytic roles.
2 types- rna
Dna
Describe the structure of a nucleotide
The sugars are- deoxyribose
Cyclic molecule- most of atoms arranged in a ring
Ring contains 1 o and 4c
5th c is attached to 4c
Deoxyribose also has oh group attacthed to 3c
Phosphate group= phosphorus atom- 4o bonded to it
What does rna consist of ?
Five c sugar- ribose
Nitrogenous base
Phosphate group
