Biology Flashcards

Mitosis

This is the replication of a nucleus into two new nucleus which is typically accompanied by cytokinesis.

Epistasis

is a form of inheritance in which a characteristic is controlled by 2 different genes at different loci, each gene having 2 alleles.

Dominant epistasis

the dominant allele of one gene (the epistatic gene) masks the effect of the other (hypostatic) gene. The ratio obtained from two double heterozygotes is 12 : 3 :1.

Recessive epistasis

the recessive allele does the masking, so the dominant allele of the epistatic gene needs to be present in order for the hypostatic gene to be expressed, the ratio obtained from two double heterozygotes is 9 :3 :4

Variation

refers to the difference that occur in the phenotype and genotype of organisms.

Intraspecific variation

occurs in members of the same species due to sexual reproduction

Sources of variation

1. Crossing over or exchange in genetic material in meiosis
2. Independent assortment of alleles due to random alignment on the spindle of the chromosomes in meiosis.
3. Random fertilizations for any male gametes can fertilize any female gametes.

Gene

is the length of DNA that codes for a specific polypeptide

Double stranded Chromosome

has 2 sister chromatids, that are identical to each other having the same allele at the same loci

Karyogamy

this is a map of all chromosomes, obtained by karyotyping.

Phases of interphase

1. G1
2. S
3. G2

G1- Phase

This is the first growth phase, cellular contents double and materials for DNA synthesis accumulate.

S-Phase

This is the synthesis phase, DNA replicated and chromosomes become double stranded.

G2-Phase

This is the second growth stage proteins which are needed for cell division are synthesized including microtubules.

Stages of Mitosis

Interphase

Prophase

Metaphase

Anaphase

Telophase

Interphase

Not seen as an actual stage of mitosis.

Nucleus is still intact

Replicates in a semiconservative manner to avoid errors.

Is 95% of the cell cycle

Nuclear materials seen like thread like structures chromatids.

Prophase

Chromatids start to condense into chromosomes

chromosomes become visible

nucleus membrane disassociates

centrioles move apart

microtubules become spindle

Mutation

this is the change in DNA structure or the amount of DNA in a an organism

Metaphase

Nuclear membrane has broken down allowing chromosomes to move.

Chromosomes randomly align at the equator of the spindle. Spindle fiber attach to the centromeres at the kinetochore.

Anaphase

The centromeres split.

Spindle fibers contract pulling chromatids apart which move to opposite poles.

Telophase

Opposite of prophase

Spindle fibers breakdown

Chromosomes unwinds and become chromatids once again

Nuclear membrane reforms around each set of chromosomes.

Cytokinesis in Animal Cells

This is when invagination takes creating a cleavage furrow moves inward forming 2 cells

Cytokinesis in plant cells

Since the cell wall has to be formed the Golgi vesicles export materials to form new cell walls which separates the cell into teo parts

Genetic Engineering

involves the manipulation of genes by removing DNA from one
organism and placing it into the genome of another.

Purposes of Genetic Engineering

Using another organism e.g. bacteria to produce a product such as human insulin

Altering the phenotype of an organism in some way by inserting foreign genes
into its genome, creating GMOs (genetically modified organisms) in order to
improve some aspects of the organism

Gene therapy, which involves delivering genes into cells to treat a genetic
disorder e.g. cystic fibrosis. (this area has not been very successful and now a
gene editing tool –CRISPR , shows more promise)

Use of Bacteria in Genetic engineering

Have tiny rings of DNA called plasmids, in addition to DNA in
the nucleoid, which have antibiotic resistant genes – these are used
as vectors to deliver the gene of interest into a cell

Can be used to express a gene and make a product, as they are
very small and multiply rapidly

Have enzymes called restriction endonucleases which are used to
cut the DNA of invading viruses (bacteriophages). They recognize
and cut a particular base sequence and are used as “molecular
scissors” in GE

Enzymes used in GE

Restriction Enzyme

DNA Ligase

Reverse transcriptase

DNA Polymerase

Restriction Enzyme

These cut DNA at a particular sequence in a palindromic way. The same enzyme is used to cut out the gene of interest from a cell as well as cutting the bacterial plasmid, so that the exposed bases in each are are complementary to each other. Staggered cuts create “sticky ends” which give a more secure join when they are put together.

DNA Ligase

molecular glue, joins sections of DNA covalently

DNA Polymerase

used to make multiple copies of DNA from free nucleotides in the polymerase chain reaction

Reverse Transcriptase

found in retroviruses (viruses which have RNA and not DNA). They are able to convert RNA to DNA, which is the reverse of transcription.

Stages in GE

Gene isolation – finding the gene of interest i.e. the one which is going to be expressed

Copying the Gene – many copies of the gene of interest have to be made

Inserting the gene into a vector – plasmids need to be cut open and the gene of interest
inserted and joined up

Inserting the vector into a cell – the recombinant gene is now carrying the gene of
interested and needs to be placed in the cell, where it will be expressed

Screening – the cells that have the vector with the foreign gene need to be identified ( as
the process is only about 1% will be successful)

Cloning – bacteria that have successfully taken up the genes will be allowed to multiply
and make the product

Gene Isolation

Can be cut out of the genome of the cell using restriction enzymes (the same one
that will cut the plasmid)

Can be made by reverse transcription by extracting RNA from the cells that are
expressing the gene and using reverse transcriptase to make cDNA

Can be assembled in a lab from free nucleotides if the sequence is known. This is
called gene synthesis cloning.

Gene synthesis cloning

the assembling of free nucleotides when the sequence is known

Processes involved in Polymerase Chain Reaction

DNA polymerase and short lengths of DNA called
primers are loaded into the machine

A series of heating and cooling take place

Heating opens the DNA and complementary
nucleotides are added

Multiple copies of the gene are made in a short time.

Methods of inserting a vector

Micro-injection

Micro-projectiles

Electroporation

Liposomes

Micro-injection

a very fine pipette is used to inject the DNA into the cell

Micro-projectiles

minute pellets of a heavy metal coated with DNA are shot into a cell at very high speed

Electroporation

rapid brief electrical pulses create temporary gaps in the cell
membrane of the host cell, allowing the DNA to enter.

Liposomes

tiny spheres formed from plasma membrane with DNA in them – these pass easily through the cell membrane

Biochemistry

This is the study of chemicals of living organisms

4 most common elements in living things

1. hydrogen
2. Carbon
3. oxygen
4. nitrogen

4 most common earth elements

1. oxygen
2. silicon
3. aluminum
4. sodium

What is responsible for the acidic nature of fatty and amino acids?

The carboxylic group (COOH)

Unsaturated bonds

Compounds containing double or triple carbon-carbon bonds eg ethene C2H4

Polarity

This is the uneven charge distribution within a molecule

Dipole

This is when in a molecule one part/pole is slightly negative and the other is slightly positive

Transpiration

The loss of water from plants to the atmosphere outside mainly through the stomata of the leaves

Phloem

Transport solutes and photosynthesis products specialized for the movement of organic and inorganic materials

Xylem

Conducts water and minerals upwards from the roots to the other parts of the plant

How much percentage of blood is water?

Approximately 90%

What is the H-O-H angle?

105 °

Liquid water has what kind of shape?

A tethadral shape

What kind of bonds does water have?

Polar covalent bonds

What kind of molecule is water

A polar molecule

What are hydrogen bonds?

Hydrogen bonds are the forces of attraction formed when slightly positive regions of a water molecule come close to the slightly negative regions of another water molecule.

What causes the high cohesive strength of water?

It is caused by the presence of hydrogen bonds

Surface tension in water is......

High

What is cohesion?

This is the force whereby individual molecules stick together

What is maximum density of water?

Maximum density is achieved at 4°C

Water has a \______ heat of vaporization and fusion

High

What is vaporization?

This is the amount of heat required to convert liquid water into gaseous water.

Liquid water has a \______ specific heat capacity.

High

What is specific heat capacity?

Specific heat capacity is the amount of energy required to raise the temperature of 1 kg by 1°C.

What is Zooxanthellae?

These are microscopic algae that live in a symbiotic relationships with coral polyps.

What is hydrophobic interaction?

This is the action of the non polar molecules clustering together.

What happens in the ionisation of water?

One of the hydrogen atoms leaves the oxygen atom to which it is covalently bonded and jumps to the oxygen atom of another water molecule where it becomes hydrogen bonded.

In ionization of water

what is produced?

What is concentration?

This is the number of solute particles per unit volume.

What is a alkaline solution?

This is one in which the concentration of OH- exceeds the concentration of H+

What is an acid?

This is a substance that causes the concentration of hydrogen ions to rise above its equilibrium value of 1 x 10 -7 molL-

Acids are considered as \_______________

These are proton donors

What is a base?

This is a substance that causes a decrease in the relative numbers of H+

Bases are considered as \_____________

Proton acceptors

What is alkali?

This is a soluble base.

What are strong acids and bases?

These are substances that ionize almost completely in solution resulting in large increases of H+ and OH-

What is pH value?

This is defined as the negative logarithm of the H+concentration in molL- which is the same as the reciprocal of H+ concentration.

What is the equation to calculate pH?

This is -Log[H+]\=log[1\H+]

What are buffers?

These are chemical systems that maintain a relatively constant pH when small amounts of acids or bases are added to a solution.

What makes up a buffer?

It is a mixture of weak acids and its corresponding salt which provides a reservoir of the acid and its anion.

What is an example of a buffer?

An example is carbonic acid (H2CO3) and its salts

What is most abundant organic molecule in nature?

Carbohydrates

What is the primary energy store molecules in most living organisms?

Carbohydrates

What type of bonds are in carbohydrates?

C-C and C-O bonds

What are monosaccharides?

This consists of a single sugar molecule.

What are some examples of monosaccharides?

Glucose and frustose

What are dissacharides?

These contain 2 sugars covalently linked together by

What are some examples of disaccharides?

Examples are sucrose and lactose

What is ratio of H:O in carbohydrates?

Carbohydrates are 2:1

What are polysaccharides?

These contain many sugar units covalently bonded together.

Polysaccharides are also called \_________________________

Macromolecules

What is polymerisation?

This is when monomers or individual sugar unit are covalently linked together to create a polymer.

What causes the units to link together?

By the process of condensation (removal of water )

What causes the units to break down?

By the process of hydrolysis which is the opposite of condensation

What are the 3 main types of macromolecules ?

They are polysaccharides

What are polysaccharides used for?

They are used for food storage and structural purposes.

What types of molecules are nucleic acids and proteins?

They are informational molecules

What are some properties of carbohydrates?

Some are all are aldehydes or ketones and all contain several hydroxyl groups

How are monosaccharides classified?

According to the number of carbon atoms such as trioses (3C)

What are the most simplest monosaccharides?

They are trioses