The cell Flashcards
What are the levels of organisation in biology?
Atoms - Molecules [Chemical level : atoms combine to form molecules] - organelle - cell [ cellular level : cells are made up of molecules] - tissue [ tissues contain similar types of cells] - organ [organ level : organs are made up of different types of tissues] - organ system [organ system level : organ systems consists of different organs that work together closely] - organism [organism level : the human organism is made up of many organ systems
Why is the cell important?
- The cell is the basic structural and functional unit of living organisms
- Cells provide structure and support to the body of an organism
- The nucleus [major organelle] carries genetic information necessary for reproduction and cell growth
What is DNA?
DNA stands for Deoxyribonucleic acid
Nucleic acids are made up of monomers named nucleotides
What makes up a nucleotide?
- Phosphate group
- Sugar - deoxyribose
- Nitrogenous bases
Where are karyotypes obtained?
Karyotypes are obtained from cells that are actively replicating, specifically cells that are in the metaphase or about to enter into the metaphase
Briefly describe DNA Replication.
- Helicases unwind the parental double helix
- Single - strand binding proteins stabilize the unwound parental DNA
- The leading strand is synthesized continuously in the 5’ - 3’ direction by DNA polymerase
- The lagging strand is synthesized discontinuously. Primase synthesizes a short RNA primer, which is extended by DNA polymerase to form an Okazaki fragment
- After the RNA primer is replaced by DNA [by another DNA polymerase], DNA ligase joins the Okazaki fragment to the growing strand
What is DNA also good for?
DNA creates RNA molecules which is functional[on its own] in the cell. DNA also creates protein
Differences between DNA and RNA.
RNA exists as a single strand and DNA has to always be in a double strand. RNA has a beta - ribose sugar and DNA has a beta -2- deoxyribose. RNA contains a deaminated version of cytosine
What is a gene?
A gene is all the information of the genome sequence that would be represented in the primary [preprocessed] RNA transcript if the gene were to be expressed - this means that the 5’ and 3’ UTRs, noncoding exons and introns are included but the regulatory parts, unless transcribed, are not
The steps of the transcription of a gene are as follows :
- Initiation
- Elongation
- Termination
Name the types of gene products.
- Messenger RNA - the RNA that will become a protein
- Non - coding RNA : RNA that will not become a protein
- miRNA
- siRNA
- snRNA
- piRNA
- lnRNA
- tRNA
Why is the amino acid, methionine, important?
Methionine is important as it is the start codon [AUG] - Protein synthesis starts here
Non-Polar amino acids :
- Glycine
- Alanine
- Valine
- Cysteine
- Proline
- Leucine
- Isoleucine
- Methionine
- Tryptophan
- Phenylalanine
Polar amino acids :
- Serine
- Threonine
- Tyrosine
- Asparagine
- Glutamine
Amino acids with a positive charge :
- Lysine
- Arginine
- Histidine
