Biology Flashcards
Highlights the bold face words in the section of biology
Prokaryotic
“before nucleus” ; cells lack a membrane-bound nuclei, as well as membrane bound organelles. DNA forms a circular pattern
What are the main components of a prokaryotic cell?
Ribosome and genetic material
What are the 6 kingdoms?
Bacteria, Archaea, Protista, Fungi, Plante, Animalia
Histones
Structural proteins around which DNA winds to form chromosomes. They also regulate gene transcription.
Nucleolus
A dense structure inside the nucleus where ribosomal RNAsynthesis occurs.
rRNA
Necessary for protein synthesis at the ribosome. The most abundant of all RNA types. Found in the nucleus. mRNA passes through 2 subunits and is translated into amino acids.
Ribosome
Sites of protein production. They are synthesized by the nucleus. They can be found free-floating in the cytoplasm or bound to the outer layer of the endoplasmic reticulum.
Endoplasmic Reticulum
Involved in the transport of materials throughout the cell. Comes in two forms: smooth ER and rough ER.
Smooth ER
Does not contain ribosome. Is involved with metabolism and production of lipids.
Rough ER
Contains ribosome and plays an important role in the production of proteins
Golgi apparatus
Receives vesicles from the smooth ER and modifies them, repackage them, and distributes them to the cell surface for exocytosis
Mitochondria
Site of aerobic respiration and the supplier the form of ATP. Contains an inner and an outer phospholipid bilayer
Cytosol
The fluid within a cell that is a part of the cytoplasm.
Karyokinesis
Nuclear division
Cytokinesis
Cell division
Eukaryotic
A cell type with a nucleus; DNA has a linear shape and cells contain membrane bound organelles
Vacuoles/vesicles
Membrane bound sacs involved in the transport and storage of materials that are ingested, secreted, processed, or digested by the cell. Vacuoles are larger than vesicles and found most commonly in plant cells.
Centrioles
Composed of microtubules; Involved in spindle organization during cell division. Animal cells have a pair of centrioloes oriented at right angles to each other. Plants do not contain centrioloes.
Lysosomes
Contain hydrolytic enzymes. The cell uses them in intracellular digestion. When lysosomes erupt they cause self-destruction of the cell.
Stages of cell division
Interphase - duplication Prophase - dissolution of nuclear membrane and condensation Metaphase - Lining up Anaphase - Break apart Telophase - reset
Cell Theory
All living things are composed of cells.
The cell is the basic functional unit of life.
The chemical reactions of life take place inside the cell.
Cells arise only from pre-existing cells.
Cells carry genetic information in the form of DNA.
What is a nucleotide composed of?
Deoxyribose bonded to a phosphate group and a nitrogeneous base. The bases can be either a purine or a pyramidine.
In DNA, what are the purine bases?
Adenine and Guanine. These have a two ring nitrogeneous base.
What are the pyramidine bases?
Cytosine and Thymine. These have a one ring nitrogeneous base.
3’ and 5’
Refers to the number of the carbon on the sugar molecule at the terminus of the DNA strand
Pairing of DNA strands
Purine bonds with pyrimidine; T forms 2 hydrogen bonds with A and G forms 3 hydrogen bonds with C
Topoisomerase
Uncoils the DNA strands
DNA helicase
Breaks the hydrogen bonds between the nitrogeneous bases of the individual nucleotides
DNA polymerase
Reads the individual parent strands and creates a complimentary antiparallel daughter strand
What direction does DNA polymerase read in?
It reads the parent strand in a 3’ to 5’ direction and creates a strand in a 5’ to 3’ direction
Okazaki Fragments
Short fragments resulting from the continuous jumping of the DNA polymerase as the original strand unzips. The fragments of the lagging newly synthesized strand are then joined together by DNA ligase
Nucleosides of DNA and RNA
Adenine, Thymine, cytosine, and guanine
Thymine is transcribed as Uracil in RNA synthesis
Central Dogma of Molecular Genetics
DNA is the basis for heridity
DNA self-replicates passing its code to future generations
DNA transcripts into RNA which translates into proteins
What are three differences between DNA and RNA?
The sugar is ribose instead of deoxyribose.
It contains Uracil instead of Thymine.
It is usually single stranded.
RNA can be found in both the nucleus and cytoplasm of the cells.
mRNA
Transports a complement of the DNA sequence to the ribosomes
tRNA
Found in the cytoplasm. It brings amino acids that are coded for on the mRNA strand to the ribosomes; each amino acid contains aminoacyl-tRNA synthetase that helps it bind to tRNA
Sequence of transcription
This is how a strand of mRNA is created.
- RNA polymerase binds to a promoter region of DNA. Transcription factors assist with the binding.
- Transcription proceeds in a 3’ to 5’ direction in a process similar to DNA replication
- Post-transcriptional processing take place. Extra sequences called intron are added, along with a guanine cap and poly-A tail. These additions protect the exons from enzyme degradation when RNA leaves the nucleus.
Sequence of translation
- Initiation - binding of ribosome to mRNA and scanning of sequence to find start codon.
- Elongation - hydrogen bonds form between mRNA at the A site of ribosome and its anticodon on tRNA. Then a peptide bond form between amino acid on tRNA at the A site and tRNA at the P site. Then moves along.
- Translation - the ribosomes advances every three nucleotides on mRNA
- Termination - when a stop code arrives at the A site of the ribosome.
- The aminoacid strand releases and takes on a 3 dimensional configuration with primary, secondary, and tertiary folding.
Catabolic reactions
A reaction of metabolism that breaks down large chemicals and releases energy
Anabolic reactions
A metabolic reaction that builds up large chemicals and requires energy
Respiration
Consumption of oxygen by the body. The oxygen is then used to convert glucose into ATP.
External respiration
The entrance of air into the lungs and the gas exchange between alveoli and the blood
Internal respiration
The exchange of gas between the blood and cells and the intracellular processes of respiration
Glycolysis
Breaks down glucose molecules in two phases, one requires energy and one creates energy. The net product is 2 molecules of ATP, two molecules of pyruvate, and two molecules of NADH. Glycolysis takes place in the cytosol of a cell.
Fructose-1,6-biphosphate
The unstable product of adding two phosphates to a glucose molecule in glycolysis. The phosphates come from 2 ATP molecules
What are the end products of the energy requiring phase of glycolysis?
DHAP and glyceraldehyde-3-phosphate. These are isomers of each other. Only the glyceraldehyde-3-phosphate can be used in the next stage. The DHAP requires conversion to glyceraldehyde-3-phosphate and can then proceed.
What are the products of the energy releasing stage of glycolysis?
Pyruvate (a three carbon molecule), four ATP and two NADH
Phosphofructokinase
Catalyzes the formation of the unstable, fructose-1,6-biphosphate. This enzyme can speed up or slow down glycolysis in response to energy needs in the cell. It is the limiting factor then?
What happens to pyruvate?
In the presence of O2 it can be further oxidized to carbon dioxide creating more molecules of ATP. This is done during pyruvate oxidation, the citric acid (or kreb’s cycle), and oxidative phosphorylation
Fermentation
NADH donates it’s electrons to an acceptor molecule in a reaction that does not generate ATP but does regenerate NAD+ so glycolysis can continue. This is used mostly by bacteria
Acetyl CoA
Produced from the oxidation of pyruvate. This is the starting molecule of the citric acid cycle.
The citric acid cycle
Takes place in the mitochondria in eukaryotes and in the cytoplasm in prokaryotes. This is a closed loop cycle that takes place over 8 steps. The cycle releases two CO2 molecules and produces 3 NADH, 1 FADH2, and one ATP. One glucose molecule can drive the cycle twice.
