Review midterm Môn Biology Technology | Trường Đại học Quốc tế, Đại học Quốc gia Thành phố Hồ Chí Minh

lOMoAR cPSD| 59085392 Bio
1) Distinguish between saturated and unsaturated fats and between cis
and trans fat molecules.
*saturated and unsaturated:
-The difference between saturated and unsaturated fat lies in the
number of double bonds in the fatty acid chain. Saturated fatty
acids lack double bonds between the individual carbon atoms,
while in unsaturated fatty acids there is at least one double bond in the fatty acid chain.
- Saturated fats tend to be solid at room temperature and from
animal sources, while unsaturated fats are usually liquid and from plant sources.
*cis and trans fat molecules. Cis Fat Trans Fat
Arrangement The chains of carbon atoms Hydrogen atoms are on the
of atoms are on the same side of the opposite side of the double double bond, resulting in a bonds of the carbon chain, kink. making the fat molecule straight.
Melting Point Usually low. Some cis fats are Usually high. Trans fats, like liquid at room temperature. saturated fats, are solid at room temperature.
2) What is radioactive isotope? Describe one application of using
radioactive isotope in medicine or biological research.
A radioactive isotope is any of several species of the same chemical
element with different masses whose nuclei are unstable and
dissipate excess energy by spontaneously emitting radiation in the
form of alpha , beta , and gamma rays. Every chemical element has
one or more radioactive isotopes. For example, hydrogen, the lightest
element, has three isotopes, which have mass numbers 1, 2, and 3.
In medicine, for example, cobalt-60 is extensively employed as a
radiation source to arrest the development of cancer. Other
radioactive isotopes are used as tracers for diagnostic purposes as
well as in research on metabolic processes.
3) Describe major differences in photosynthesis among C3, C4 and CAM plants. lOMoAR cPSD| 59085392
C3 photosynthesis produces a three-carbon compound via the Calvin cycle
while C4 photosynthesis makes an intermediate four-carbon compound that
splits into a three-carbon compound for the Calvin cycle. Plants that use CAM
photosynthesis gather sunlight during the day and fix carbon dioxide molecules at night. Sto Type Seperation in initial mata Best
CO2 fixation and Calvin ope adapted cycle n to Cool, wet environme C3 No separation Day nts
Between mesophyll and Hot, sunny bundle-sheath cells (in Day environme C4 space) nts Very hot, dry Between night and day environme CAM (in time) Night nts
4) Name the three stages of cellular respiration; for each, state the region of the
eukaryotic cell where it occurs and the products that result.
There are three main stages of cellular respiration: glycolysis, the citric acid
cycle, and electron transport/oxidative phosphorylation. 1. Glycolysis
Glycolysis occurs in the cytoplasm of cells, outside of mitochondria
Products: The 2 pyruvic acids , net gain of 2 ATP (2 are invested to split the glucose, and
4 are formed from ADP and P) , 2 NADH, 2ADP
2. the citric acid cycle occurs in the matrix of the mitochondria lOMoAR cPSD| 59085392
Product: 2ATP, 4CO2, 2FADH2, 6NADH 3. Electron
Transport Chain the inner membrane of the mitochondria Product: 34 ATP, 6H2O
Glycolysis occurs in the cytosol producing (for 1 Glucose) 2 pyruvate + 2 NADH + 2 ATP
Citric Acid Cycle occurs in the matric of the mittochondira where it produces (for 1
pyruvate): 4 NADH, 1 FADH2, 1 ATP, 3 CO2
Oxidative phosphorylation also occurs in the matrix of the mittochondira producing
1 NADH --> 1 NAD+ + 1/2 H2O + 2.5-3 ATP
1 FADH2 --> 1 FAD + 1/2 H2O + 1.5-2 ATP
5. Describe the fluid mosaic model of cellular structure.
• The plasma membrane, also known as the cell surface
membrane or plasmalemma, defines the boundary of the cell.
They are a special type of membranes which are lipid structures
that separate the cell from its environment.
• In composition, it is a phospholipid bilayer with embedded
proteins that enclosing every living cell.
• It serves some specific functions such as controlling the flow of
nutrients and ions into and out of the cells, mediating the response
of a cell to external stimuli (a process called signal transduction),
and interacting with bordering cells.
The fluid mosaic model describes the structure of the plasma membrane as a mosaic of
components —including phospholipids, cholesterol, proteins, and carbohydrates—that
gives the membrane a fluid character.
6. What is epigenetic Inheritance? Explain how histone acetylation affect
chromatin structure and the regulation of transcription? lOMoAR cPSD| 59085392
epigenetic Inheritance : An inheritance pattern in which a modification to a gene or
chromosome alters gene expression in an organism, but the expression is not changed
permanently over the course of generations histone acetylation
Chemical modifications to histones play a direct role in the regulation of gene transcription.
The N-terminus of each histone molecule in a nucleosome protrudes outward from the nucleosome.
These histone tails are accessible to various modifying enzymes, which catalyze the
addition or removal of specific chemical groups.
In histone acetylation, acetyl groups (—COCH3) are attached to positively charged lysines
in histone tails Deacetylation is the removal of acetyl groups.
When the histone tails of a nucleosome are acetylated, their positive charges are
neutralized and they no longer bind to neighboring nucleosomes
Histone acetylation enzymes may promote the initiation of transcription not only by
modifying chromatin structure, but also by binding to, and "recruiting," components of the transcription machinery.
Acetylation enzymes may promote the initiation of transcription via binding and recruiting components of transcription. 7.
Distinguish between the following pairs of terms: dominant and recessive;
heterozygous and homozygous; genotype and phenotype
Dominant: determines organism's appearance
Recessive: has no noticeable effect on appearance
Homozygous: pair of identical alleles
Heterozygous: pair of different alleles Genotype: genetic makeup
Phenotype: appearance or observable traits
8.Describe meiosis process and explain how this process contributes to genetic variation in species. lOMoAR cPSD| 59085392 Interphase
Replication of DNA in preparation for meiosis. After replication,
each chromosome becomes a structure comprising 2 identical chromatids. Prophase I
The chromosomes condense into visible X shaped structures that
can be easily seen under a microscope, and homologous
chromosomes pair up. Recombination occurs as homologous chromosomes exchange DNA.
At the end of this phase, the nuclear membrane dissolves. Metaphase I
Paired chromosomes line up along the middle of the cell. Anaphase I
The pairs of chromosomes separate and move to opposing poles.
Either one of each pair can go to either pole. Telophase I
Nuclear membranes reform. Cell divides and 2 daughter cells are formed. Prophase II
There are now 2 cells. DNA does not replicate again. Metaphase II
Individual chromosomes line up along the middle of the cell. Anaphase II
The chromosome copies (chromatids) separate and move to opposing poles. lOMoAR cPSD| 59085392 Telophase II
Nuclear membranes reform. There are 4 new haploid daughter
cells. In males, 4 sperm cells are produced. In females, 1 egg cell
and 3 polar bodies are produced. Polar bodies do not function as sex cells.
During fertilisation, 1 gamete from each parent combines to form a zygote. Because
of recombination and independent assortment in meiosis, each gamete contains a
different set of DNA. This produces a unique combination of genes in the resulting
zygote. Recombination or crossing over occurs during prophase I. Homologous
chromosomes – 1 inherited from each parent – pair along their lengths, gene by
gene. Breaks occur along the chromosomes, and they rejoin, trading some of their
genes. The chromosomes now have genes in a unique combination. Independent
assortment is the process where the chromosomes move randomly to separate poles
during meiosis. A gamete will end up with 23 chromosomes after meiosis, but
independent assortment means that each gamete will have 1 of many different combinations of chromosomes.