2.69) Urinary System

Describe the structure of the urinary system, including kidneys, ureters, bladder and urethra

We have two kidneys, each with it's own blood supply, carrying out the process of filtration and osmoregulation. For each kidney, there's a tube that lead to the bladder called ureter, which carries urine. There's one bladder for two ureter and is conducted to the outside of the body to be excreted down the urethra, which either travels down into vagina or penis. 

2.68) Excretion and Osmoregulation

Understand how the kidney carries out its roles of excretion and of osmoregulation

Kidneys carried out the excretion of molecules called urea, containing nitrogen which is toxic to the body and cannot be stored. The form of nitrogen circulating in our body and are potentially toxic can be found in the amino acids which are used to growth, however, excess amino acids must be removed. Both liver and kidneys carry out the function to remove urea.

First, the blood circulated to the liver and amino acids are broken down and converted into molecules called urea. This reenter the blood stream that's to be removed to the and circulate into both kidneys. The kidneys will filter the urea from the blood and will be added to water to form urine, which drains down the ureter to collect in the bladder. The urea has now been removed from the body and is collected in the bladder in the form of urine.

The filtered blood returned to the circulation and travels back to blood stream with the toxic urea removed.  

Osmoregulation

Osmo - osmosis

Regulation - control

Osmoregulation - the control of osmosis

Hypertonic - 

Hypotonic - 

The tissue fluid which surround body cells must be isotonic with the cytoplasm of the cell (the amount of water going in and out of the cell are equal) so that cells remain the same size and shape and maintain their function. Blood circulating into the tissue may too concentrated and cause hypertonic tissue fluid or maybe too dilute causing a hypotonic tissue fluid. Hypertonic would remove too much water and cause the cell to shrink, and hypotonic would add too much water and cause the cell to swell. 

We can keep the tissue fluid isotonic to the cell cytoplasm by controlling the composition of blood. Blood forms the tissue fluid. The role of kidney is to control the composition of blood. It removes excess water and salts and excrete them down the ureter. 

By controlling the amount of water and salts in the blood and therefore keep the tissue fluid isotonic. 

2.67b) Human organs of Excretion

Recall that the lungs, kidneys and skins are organ of excretion

1. Lung x 2- release metabolic waste CO2 (carbon dioxide)

2. Kidney x 2 - excretion of excess water 

- molecule urea (nitrogen waste from amino acid as we can't store it so we excrete them) 

- salts

3. Skin - water & salts --> sweat

- little bit of urea

2.67a) Excretion in plants

Recall the origin of carbon dioxide and oxygen as waste products of metabolism and their loss from the stomata of a lead

1. The process of photosynthesis absorbed light energy. It combines Carbon dioxide with Water to form molecules of Glucose and gives of the gas Oxygen, which is considered a waste molecule.

6CO2 + 6H2O ---sunlight---> C6H12O6 + 6O2

2. The process of aerobic respiration requires glucose and oxygen, as they go through enzyme reaction, the glucose molecule is broken down and the energy is used to produced ATP (adenosine triphosphate) as energy and we get the waste of carbon dioxide and water. 

C6H12O6 + 6O2 ---enzymes--> ATP + 6CO2 + 6H2O

In conclusion, plant excretes carbon dioxide and oxygen depend upon whether they're doing respiration or photosynthesis. 

3.10) Menstrual cycle

Understand the roles of oestrogen and progesterone in the menstrual cycle

Oestrogen and progesterone are both hormones, which is produced in the structure called endocrine gland. Hormones will travel through the blood to the target tissue, where the hormone will have effects on.

The ovary is the endocrine gland for (produces) oestrogen that will travel through the blood stream to the lining of the uterus.

The effects of estrogen include:

1. The lining of uterus (wall of endometrium) thickens

2. Flows through the blood stream to out brain and brings the release of sex hormone (LH). It reaches its peak by day 13 of the cycle and causes the ovary to release an egg into the oviduct, where it is possible for fertilization to occur. 

During this first half of menstrual cycle, a circular structure becomes larger and larger. Inside this falloco is the egg. The cells around the fallocal are producing oestogen. It reaches it maximum size by day 13 and causes its wall to rapture and the egg is released. 

LH causes ovulation, the release of the egg.

Now that the fallico is released, the now emptied structure changes its function and develops into the yellow color. This gives us the name corpusinteum that produce progesterone. 

Progesterone travels through the blood stream to the lining of uterus. 

3. This prevents the lining of uterus from breaking down. This makes it possible that the fertilized egg then can plant into the wall of endometrium and develops into pregnancy. 

4. If no fertilized egg is planted into the wall of endometrium, then it will break down and form what we known as menstrual period/bleeding. 

This mark the end of one menstrual cycle. When the lining is broken down completely, the whole process would repeat. 

3.34) Causes of mutation

Understand that the incidence of mutations can be increased by exposure to ionizing radiation (for example gamma rays, X-rays and ultraviolet rays) and some chemical mutagens (for example chemicals in tobacco). 

Mutation is the change in base sequence of the genes, which creates new alleles.

Cases for mutation

1. Radiation such as X-Ray, UV-B ray (sunshine) that can cause diseases such as cancer

2. Chemicals… effect of tars and tobacco, which cause the change in base sequence that can lead to cancer. Chemicals which caused mutation are called mutagens and those that also cause cancer are called carcinogen. 

3.33) Antibiotic resistance

Understand how resistance to antibiotics can increase in bacterial populations

Case Study:

Bacteria Staphylococcus aureus can cause skin or lung infection. 

The antibiotic  can kill the Staphylococcus aureus. The ones that are killed are susceptible, called MSSA.

When random mutation occurred to the genome of the bacteria. When the antibiotic is applied, the bacteria did not die. This is given the name resistant, creating a new type of bacteria known as MRSA. 

As a result, mutation has created genes that allow bacteria to break down the antibiotic, resisting it and survived. This form of the bacteria increasingly survives and becomes more common. 

This can become serious problem in hospitals and treatment. 

3.32) Types of mutation

Understand that many mutations are harmful but some are neutral and a few are beneficial

The process of mutation creates new alleles.

As the alleles are responsible for the phenotype, the impact could be that they are beneficial, harmful, or neutral (no effect).

Example:

Beneficial - improve efficiency of enzyme

Harmful - mutation leads to production of enzyme that doesn't work (nonfunctional)

Neutral - the mutation leads to a second or new allele that has no particular affect. However, the neutrality might not last forever due to environmental change, etc, which in time can make it become beneficial or harmful. 

3.31) Evolution

Describe the process of evolution by means of natural selection

Evolution

- change in form of organisms (new forms arising)

- change in frequency (how many) of alleles

Natural Selection 

- the mechanism of evolution (first proposed by Charles Darwin)

Example:

a bacteria staphlococcus aureus which can lead to skin and lung infection

The original form of such bacteria is sustained to be kill by methecilline, which is a type of antibiotic. (They are susceptible to the antibiotic.) MSSA

What happened is that a random mutation to the genome of the bacteria allowed us a characteristic of 'breaking down methecilline.' This means that it is no longer killed by the antibiotic. This new form is called the Resistant form, MRSA.

[Refer to definition number 1 of evolution]

Because the MRSA is resistant to the antibiotic, they became increasingly common (increase in frequency of the allele) 

[Refer to definition number 2 of evolution]

Two features of natural selection (process):

1. Random mutation - produce MRSA form 

2. Non-random selection - due to anti-biotic which is selecting the MRSA to survive and MSSA to be selected and killed

3.30) Mutation

Recall that mutation is a rare, random change in genetic material that can be inherited

In every DNA, there is what we called the base sequence, which cause the gene. The form of the gene is called allele. Certain process or event can result in a change of the base sequence. For example, for ACT to AAT. 

This change creates a new version of the alleles. It's possible that this allele can create an entire new protein, and have an entire different affect on the phenotype. 

Consider the dominant and recessive alleles: A and a. The reason why different alleles exist is because of the process called mutation, that changes the base sequence of the gene. 

3.29) Species Variation

3.29) Species Variation

Understand that variation within a species can be genetic, environmental, or a combination of both

Variation = differences in phenotype, by counting or measure the differences and show them in bracket form

Everyone individual has a phenotype. The phenotype is determined by the difference in genotype and environment. (continuous variation)

Different classes suggests that the variation in the species is entirely due to the variation in the genotype, with no role for the environment to play. 

For example, blood group. A, AB, B, O

Variation in the genotype can also be modified by the environment. (You can see as continuous variation) 

For example, one might inherited the genotype for being tall, but the environment such as diet also affect his height. 

Variation in population/ species that's entirely due to environmental variation. Genes have no role here. This cannot be inherited, so therefore the variation is not continuous. 

e.g.) a particular home language that you speak 

3.20) Pedigree Diagram

Understand how to interpret family pedigrees

Square - Male

Circle - Female

Filled in shapes - Inherited Condition (they are often diseases but NOT necessarily) 

These are represented by phenotype. 

Pedigree can be use to interpret that the affected condition is caused by dominant or recessive allele. 

3.21) Genetic Probability

Predict probabilities of outcomes from monohybrid crosses

Monohybrid - a hybrid that is heterozygous with respect to a specified gene

Generation 1:

Red (RR) x White (rr)

Red is dominant to white. 

---> Meiosis

The alleles are being separated. The gamete would contain one one of the two alleles with equal chance. 

Which means the gametes of red petals will be separated into (1/2)R and (1/2)R. The white petals would be (1/2) r and (1/2) r.

We then considered random fertilization by drawing table to illustrate to possible phenotypes and genotypes of the offsprings through Punnett square (Mendel's diagram). 

In this example, the genotype would all be Rr.

So the phenotype would ALL be red. 

So the probability would be 100% that you would have a red offspring. 

Generation 2:

Now we try to cross heterozygous parents (Rr) and (Rr)

We have…

25% of RR

50% of Rr

25% of rr

Genotype ratio…

RR:Rr:rr = 1:2:1

Phenotype ratio…

Red:White - 3:1

They are chances and probability. It depends on which pollen grain fertilizes with which ovule. 

3.18) c. Codominance

Recall the meaning of the terms: dominant, recessive, homozygous, phenotype, genotype and codominance.

Codominance refers to a relationship between two alleles of a gene in which both phenotypes of the genes are visible and do not over power each other in phenotype. This happens when both alleles are dominant. 

The offspring will result in an unusual third phenotype as the parents both contribute to the phenotype. The offspring's genotype would be a heterozygous of both dominant alleles.