Biology Unit Exam Prep
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describe a nerve cell
long, threadlike extensions that transmit electrical impulses from one part of the body to another.
which 3 parts are easily seen under a microscope when looking at a cell?
the nucleus, cytoplasm and cell membrane
what are inside the cytoplasm?
what's the structure of the nucleus and what's its function?
- -nuclear membrane
- -contents -> nucleolus (nucleoli)
- -DNA which forms the chromosomes
- to controll the cell processes by protein synthesis
- contains genetic information
what's the difference between the nucleus and the nucleolus
- -main organelle
- -membrane bound
- -contains DNA
- -sub organelle
- -non membrane bound
- -contains RNA
what's the function of the cell membrane?
to determine (ID) which substances (cells) enter or leave the cell. It also maintains cell integrit. Also used for communication, selective transport.
what are the characteristics of the cell membrane? what's its nickname?
extremely thin and flexible. selectively permeable (only allows certain things to enter/leave.)
what's the structure of the cell membrane?
it's composed ot lipids, proteins and carbohydrates.
Picture an endoplasmic reticulum. what's its function?
- (membrane walled canals)
- provides a tubular network that transports molecules from one cell part to another. forms mini circulatory systems.
what's included outside of the ER? what type of ER if these are included?
ribosomes . Rough ER.
what's the purpose of the ribosomes and what are they composed of?
protein synthesis and will also exist independently around the cytoplasm. they're composed of protein and RNA molecules.
ribosomes can make any kind of protein you want!
what's about the smooth ER? what's its job?
contains enzymes which is important for lipid synthesis, absorption of fats and metabolism of drugs. sounds like liver cells need them most.
Sooo anyways.... the proteins being made by the riboseomes are moved through the ER. now what?
It moves on to the golgi apparatus.
picture the golgi apparatus. What's its purpose?
- (layers of sacs near nucleus)
- refines, packages and delivers proteins synthesized on ribosomes.
- forms glycoproteins and package products.
how do these proteins look like when they arrive at golgi apparatus city? do they change? how?
enclosed in vesicles composed of the ER membrane. yes, they become chemically modified and by the end of the golgi apparatus, they are then packaged in bits of GA membrane.
picture a mitochondria. what's its purpose?
- (sausage like sacs with cristae)
- energy from certain nutrient molecules will be transformed into adenosine triphosphate (ATP) which is energy that the cell can use.
- ATP if formed by cellular respiration
name an active cell which contain many thousands of mitochiondria?
the muscle cell.
what's a lysosome?
they're the garbage disposals of the cell. they contain powerful enzymes which break down nutrients of foreign particles.
give an example of a lysosome using white blood cells.
a white blood cell detects a foreign object. it engulfs it andh they become digested with the lysomal enzymes. they also destroy worn cellular parts
what's a centrosome?
- paired group of tiny cylinders (centriols)
- function: makes spindle during mitosis
what are cell fibers?
- microfilaments: support organelles in lattice
- microtubules: bigger in lattice
what's the microvilli, cilia and flagellum?
- Microvilli: cytoplasmic extensions to increase surface area
- Cilia: made of microtubules
- Flagellum: single tail-like structure for movement.
what's that one important equation?
- C6H12O6+6O2 -> 6CO2+6H2O + ATP
- (glucose)+(oxygen) -> (Carbon dioxide)+(water)+(energy)
what is the DNA structure composed of?
- nucleotide which has
- 1. phosphate group
- 2. sugar group
- 3. nitrogen base: purines and pyrimidines
which enzyme splits open the DNA?
steps for DNA replication
- 1. DNA unzips
- 2. complimentary nucleotides match up
- 3. results in two identical copies
name the organic bases in a DNA molecule. which ones are purines and pyrimidines?
purines: adenine (A), guanine (G)
pyrimidines: thymine (T), cytosine (C)
what does the sequence: G, G, T in a DNA strand represent?
one type of amino acid.
what are the three different types of RNA and what are its purposes?
- messenger RNA (mRNA): carries information from DNA to ribosome
- transfer RNA (tRNA): carries amino acids to ribosome
- ribosomal RNA (rRNA): globular form makes up the ribosome
how do RNA molecules differ from DNA? similarities?
- -single stranded, nucleotides contain ribose rather than deoxyribose sugar.
- -RNA carry uracil instead of thymine.
- -double stranded, nucleotides contain DEOXYribose.
- -DNA carries thymine and not uracil.
- -both have guanine, cytosine and adenine.
what does the RNA polymerase do?
synthesized mRNA and it somehow "knows" which strands contain information. it knows where the genes begin or stop and knows the correct direction of the DNA.
what are codons?
three base sequence.
what needs to happen in order for protein synthesis to occur?
transcription and translation
What does transcription do? where does it occur?
- since DNA molecules are within a cell's nucleus and when protein synthesis occurs in the cytoplasm, genetic information needs to be carried from the nculeus to the cutoplasm.
- mRNA accomplishes this information by transcription.
Occurs in the nucleus
steps for transcription?
- 1. enzyme opens a section of DNA
- 2. complementary RNA nucleotides join one side of the DNA strand
- 3. enzyme triggers the release of the new mRNA molecule and closes up the DNA
- 4. the mRNA strand moves out of the nucleus in the cytoplasm.
how is the process of protein synthesis completed? what must the mRNA do? where does this occur?
mRNA has to leave the nucleus and associate with a ribosome. in order for that to happen, series of codons on mRNA needs to be converted from the "language" of nucleic acids to the "language" of amino acids. this is called TRANSLATION!
Translation occur in the cytoplasm
what does the transfer RNA (tRNA) do?
correctly align amino acids to form proteins.
at least how many tRNA's should be available? why?
20 because at least 20 different types of amino acids form biological proteins, at least twenty different types of tRNA needs to be free.
soo the tRNA carried 3 sets of nucleotides right? what are those called?
what are the two parts of the cell cycle?
interphase and mitosis.
What are the three parts of Interphase and their purpose?
- G1 phase: cell growth
- S phase: genetic material replicated
- G2 phase: growth and prep for cell division
what are the parts of a chromosome?
Chromatids and centromere.
What are the four stages of mitosis?
Prophase, Metaphase, Anaphase and Telophase
- chromosomes become visible; centrioles have replicated. nuclear envelop disappears and spindle fibers associate with centrioles and the chromosomes.
- chromosomes line up at the equator
- chromatids separate (now becomes chromosomes by themselves)
- nuclei in daughter cells reform
What's the result of mitosis?
two genetically identical cells and two cells of similar sizes
formation of sex cells and contain 1/2 of normal nuber of chromosomes (haploid)
what are the two types of gametogenesis?
oogenesis and spermatogenesis
what happens during prophase I?
tetrads form and crossing over (synapsis occurs)
what happens during metaphase I?
same as mitosis
what happens during anaphase I?
tetrads split and move to opposite poles
what happens during teolphase I?
- same as mitosis in spermatogenesis.
- unequal cytokinesis in oogenesis.
what happens during prophase II, mitosis II, anaphase II?
same as mitosis.
what happens during telophase II?
same as mitosis in spermatogenesis. unequal cytokinesis in oogenesis.
what are the results of meiosis?
- -four unique sperm with 23 chromosomes each
- -can be formed up to 100 million a day
- -one ovum and three polar bodies
- -one ovum every 28 days.
what's an hypertonic, isotonic and hypotonic soluttion?
what are solvents?
what are solutes?
example of a colloid solution?
example of a suspension solution?
dirt and water. (blood cells in plasma)
what are ion pumps? transport system?
What's active transport? examples?
transport proteins spend energy (ATP) to transfer materials across the membrane.
ion pumps, endocytosis (contain two things), exocytosis
what's ion pumps? transport?
permease system. active.
what's the two types of endocytosis and what do they do? transport?
- pinocytosis: cell "drinking"
- phagocytosis: cell" eating"
big stuff moving out
what's passive transport? examples?
describes the movement of substnaces down a concentration gradient. Does not need energy consumption. Diffusion, osmosis, filteration, facilitated diffusion, special solutions
what' osmosis? type of transport?
diffusion of water molecules across a selective permeable membrane. ex: how trees get water from their roots
what's diffusion? type of transport?
solute moving down a concentration gradient.
what's facilitated diffusion?
mediated by special proteins in cytoplasm
what's filteration? transport syste?
solutes and solvents move in one direction
what is a phospholipid bilayer? what's it's fancy name?
it has nonpolar HYDROPHOBIC tails pointing towards the inside and polar HYDROPHILIC hears forming the inner and outer faces. selectively permeable.
so what's hydrophobic and hydrophilic
hates water. loves water.
what does the cytosol consist of?
water and disolved substances like proteins and nutrients.
who is Father Gregor Mendel?
1863: used pea plants to develop "rules"
1902: used grasshoppers to determine factors (genes) were on the chromosomes
1915: used fruit flies to map chromosomes
Watson and Crick
1953: developed the model of the structure of DNA
2000: finished mapping the human genome with the HGP
the gene that hides the recessive gene
what's a gene?
unit of heredity that passes between generations
what's a genotype?
letters for a train an individual carries (always in pairs, one from mom and one from dad.)
different letters for a train (ex: Gg)
same letters for a trait. (ex: GG, gg)
the outwards expression of a genotype (ex: brown eyes)
the gene that is hidden by the dominant gene.
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