Lecture 1 Flashcards
what is the basic organizational unit of life?
the cell
what are all organisms made of?
cells
where do cells come from?
pre-existing cells
what are the two main types of cells?
prokaryotes and eukaryotes
what are the characteristics of prokaryotes? (3)
-no nucleus
-organelles have no membrane so they float freely in the cell
-single-celled
what are the two main domains of prokaryotes?
archaea and bacteria
what are the characteristics of eukaryotes?
-has a nucleus
-organelles have a membrane
-single-celled or multicelled
what are three examples of eukaryotes?
plants, fungi and humans
which cell is bigger, prokaryotes or eukaryotes?
eukaryotes
which cell contains less genetic material?
prokaryotes
where is genetic material contained in prokaryotes?
in a single circular chromosome
what may prokaryotic cells contain?
plasmids which are small circular DNA molecules
where is genetic material contained in eukaryotic cells?
in the nucleus
decribe the origin of mitochondria?
an aerobic cell was captured by an archaeal cell similar to the process of phagocytosis and both cells formed a symbiotic relationship over time
what is Bacterial Ectosymbiosis?
is a form of symbiotic behaviour in which an organism lives on the surface of another organism
what were mitochondria like originally?
free-living aerobic prokaryotes able to use oxygen to help generate ATP
did early archaeons use oxygen to generate ATP?
no
what is evidence showing that mitochondria and chloroplast support the endosymbiont hypothesis?
similar structure and proteins to early prokaryotes
what are the characteristics of model organisms? (4)
-they can grow quickly
-small
-readily available
-tractable-easy to manipulate
why are model organisms used?
They are selected for intensive study because they are most convenient for representing a large group of species
what is the central dogma of molecular biology?
flow of genetic material
what are messengers RNA’s used to make?
proteins
what are transfer RNAs used to make?
used for protein synthesis, specifically to make amino acid sequences
what are the two main steps of DNA information flow?
- DNA is transcribed
- DNA translated using ribosome
what are ribosomal RNAs used to make?
ribosomes
what are the ends of one strand of DNA like in terms of polarity?
the ends are polar meaning one end is 5’ and the other end is 3’
what are the two forms of nucleic acids?
- DNA
- RNA
what is a universal thing RNA uses to make amino acid sequences?
universal genetic code
what is RNA?
a type of DNA that gets translated into proteins
what is DNA?
the blueprint of an organism
what are the parts of a nucleotide?
- pentose sugar
- one of the nitrogenous bases
- phosphate group(s)
what are pyrimidines?
nitrogenous bases with one ring
what are purines?
nitrogenous base with two rings
which nitrogenous bases are purines?
adenine and guanine
which nitrogenous bases are pyrimidines?
uracil, thymine, cytosine
what are the differences between DNA and RNA? (2)
- sugar; RNA has ribose, DNA has deoxyribose
- bases; RNA has adenine, uracil, cytosine and guanine, DNA has adenine, thymine, cytosine and guanine
what is DNA made from?
deoxyribonucleoside triphosphates or dNTPs
what is RNA made from?
ribonucleoside triphosphates or NTPs
what are nucleotides linked by?
phosphodiester bonds
what are molecular interactions mediated by?
nonpolar interactions between molecules
how are phosphodiester bonds formed?
between the phosphate groups of one nucleotide and the sugar of another nucleotide
what are the weak attraction between molecules (4)?
- electrostatic attractions, attraction between molecules with opposite charges
- hydrogen bonds, attraction when the hydrogen on one molecule bonds with the oxygen or nitrogen on another molecule
- Van der Waals, the weak attraction between forces causes by temporary dipoles
- hydrophobic force, non-polar molecules repel water
how do nitrogenous bases pair?
adenine pairs with thymine or uracil, and cytosine always pairs with guanine
why is the DNA structure set up the way it is in terms of energy?
to make it energetically stable
what are the three forces that keep DNA strands together?
- hydrogen bonds
- hydrophobic interactions
- Van der Waals attractions
what is the point of major and minor grooves in the DNA sequence?
allows bigger or smaller proteins to bind to the DNA sequence
what does it mean that DNA strands are complementary?
the DNA strands match up at certain base pairs
why does DNA unzip?
to use as a template to form RNA
what does the complementary strand ensure?
The DNA is being transcribed as accurately as possible
what does it mean the strands in DNA are anti-parallel?
one strand runs in the 3’ to 5’ direction and the other runs in the 5’ to 3’ direction
What are the two ends of the DNA
strand composed of?
5’ end has a Phosphate group (-PO4)
3’ end has a Hydroxyl group (OH
how are DNA strands reversed or pulled apart?
with the help of protein or heat from a laboratory
