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. 

3.19 b) F1 x F1 Cross

3.19) Describe pattern of monohybrid inheritance using a genetic diagram

F1 = First Generation

3.19a) P1 x P1 Cross

3.19) Describe pattern of monohybrid inheritance using a genetic diagram
P = parents

3.18) Phenotype and Genotype

3.18) Recall the meaning of the terms: dominant, recessive, homozygous, heterozygous, phenotype, genotype and codominance

Phenotype

Genotype

3.2) Fertilization

Understand that fertilization involves the fusion of a male and female gamete to produce a zygote that undergoes cell division and develops into an embryo

The process of fertilization begins with the adults male and female.

The cells in testis and ovaries both have complete set of chromosomes (called diploid, or 2n), meaning both have 46 chromosomes each.

Theses cells divide to form cells with half set of chromosome (23 each) in the process called meiosis. We go from a diploid number to a haploid number, n. 

This leaves us with 23 chromosomes in each sperm and egg cell.

In sexual reproduction, these two cells are brought together and are joined/fused to form just one cell. This process is known as fertilization. It involved a combining of half set and half set of chromosomes to form a full set of chromosome.

n + n = 2n

This cell is called zygote, which is combination of male and female chromosomes. 

The zygote then go through a process called mitosis in which the cell will divide to give two cells (in which both contains complete set of chromosome). As a result, all cells contain 2n/diploid number of chromosome. 

When we have sufficient cells, the structure would be called an embryo. 

Such process holds through for all sexually reproducing organisms. 

3.9 b) Female Reproductive System

Recall the structure and function of the male and female reproductive systems

Before the pregnancy occur, the size of the uterus is no larger than an orange.

Structure & Function

Ovary - where meiosis occurs; production of eggs

Oviducts (fallopian tube) - carry the eggs to the uterus and where fertilization takes place

Uterus - structure in the center (womb) 

a) wall of uterus - made of muscle that stretch to accommodate a pregnancy

b) lining of uterus - accepts and develops the fertilizing eggs which will develop into the embryo and the child, as well as the development of the placenta

Uterus space - where the sperm cells and eggs cells moves … where embryo developed into unborn child

Cervix - entrance of sperm cells to the uterus 

Vagina - (where the penis is introduced at the end and the sperm cells enters the uterus)

collects sperm cells and travel them into the uterus

3.9 a) Male Reproductive System

Recall the structure and function of the male and female reproductive systems

Structures & Functions

Bladder - store urine

Testis - carry out process of meiosis that produce that gamete called sperm cells

Epididymis - tube system that store sperm cells

Vas deferens - carry sperm cells to penis during sexual stimulation

Sperm cells travel through...

Prostate - produce 20-30% of the volume of semen which contains sugars and is alkali (to neutralize the acidic secretion within the vagina)

Seminal Vesicles - produce sugar base and alkali secretion (70% of the semen in which the sperm cells can travel)

Sperm + Seminal Vesicles + Prostate ----> Semen (male reproductive fluid)

Semen travels down the...

Urethra - common tube which joins the left and right testis and the left and right vas deferens that takes semen down the penis, as well as the urine

Penis - carry sperm cells into the vagina during sexual intercourse

3.12) Amniotic fluid

3.12) Amniotic Fluid

Understand how the developing embryo is protected by amniotic fluid

Inside the uterus space surrounding the embryo is a fluid called amniotic fluid. 

The function of the amniotic fluid is to protect the developing embryo. The fluid is largely water. As a result, it cannot be compress. If any blows force is applied to the outside of uterus wall, it absorbs the pressure, preventing damage to unborn child. 

3.11) Placenta

Describe the role of the placenta in the nutrition of the developing embryo

Placenta is an organ the connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. 

(Fetus is an unborn offspring of mammals.)

(Uterus is the organ in the lower body of a woman or female mammal, where offspring are conceived and in which they are gestate before birth; the womb.)

The child in the uterus is surrounded by amniotic fluid. As a result, the child cannot digest, breath and carry out excretion. 

The placenta structure connects the maternal blood vessel into the child's blood vessel. 

The child obtains nutrition by the umbilical cord in the placenta structure growing out of the embryo, NOT out of the mother. 

Blood vessels inside the placenta, including arteries and veins, are blood vessels of the child. 

The placenta is going into the wall of uterus. 

In the blood stream of mother it would have glucose, amino acid and fats which will travel through her blood stream (maternal blood vessel) and into the wall of the uterus. There, the molecules will cross into the child's blood at the placenta. Then such molecules will go from the mother's blood into the child's blood, crossing the placenta.

The placenta has a large surface area and thin barrier. 

The child also produce waste such as carbon dioxide and urea into the mother's blood who will be responsible of the excretion. 

3.24) Mitosis (a-c)

Understand that division of a diploid cell by mitosis produces two cells which contain identical sets of chromosomes.

Mitosis - cell division which results in growth which occurred by increase in number of cell

A normal cell with its nucleus. The number of chromosome in the nucleus is called the diploid number (abbreviated 2n). For human, 2n = 46. 

In the process known as mitosis, a cell will divide into two cells, each with a nucleus. Each nucleus contains diploid number of chromosomes. The two cells are identical in which sometimes are described as daughter cells.

- They have the same number of chromosomes.

- They have the same set of chromosomes. 

How are the copies of chromosomes made? How did they separate into two cells?

The original cell has to copy its chromosomes in the process called DNA replication. In this process, each chromosome undergrowth and copy process to form an identical copy of the cell with the same genes and same alleles. The two copies are held together by a structure around the center region known as the centromere. The pair is called pair of chromatids. 

The process of DNA replication takes place inside the nucleus while it's still intact. This resting stage of cell cycle is known as the interphase. 

The Stages of Mitosis

During the interphase, the process of DNA replication occurs. We are not able to observe the chromosomes.

1. Prophase: Nuclei member breaks down and the chromosomes become visible as a pair of chromatids.

2. With the nucleus gone, inside the cell, a network of protein molecules known as the spindle/ spindle fibres formed. This extends from one pull of the cell to the other. Late prophase: The chromosome pairs will move toward the spindle and will join with the spindle fiber in the center. 

3. Metaphase: The pair of chromatids are attached to the spindle fibre by the centromere. The characteristic is the chromosomes are in the middle across the equator of the cell.

4. Anaphase: The spindle fiber shortened, pulling each chromosome in opposite direction and the pair of chromatids are moving apart toward each poles. (They're separated.) 

5. Telophase: The nucleus beings to reform around chromosomes at either end of the cell. (The formation of two nuclei at opposite ends of the cell.) 

6. Cytokinesis: The cell splits into two. This is NOT part of mitosis. It is a particular independent stage. 

The daughter cells each contain a chromosome, which is the same as the parental cell. In human cell, we see 23 pairs of chromosomes separating at the same time. 

3.16) DNA and Genetic Information

Describe a DNA molecule as two strands coiled to form a double helix, the strands being linked by a series of paired bases: adenine (A) with thymine (T), and cytosine (C ) with guanine (G)

A chromosome is likely to contain thousands of genes. Taking one gene locus and expand the small section of chromosome will find the Double Helix shape, which appears to be parallels. 

The strand of the Double Helix are called the "Sugar-phosphate backbone." 

In the centre we find a group of molecules we called "bases" and there appears to be 4 different types of bases --- adenine (A), thymine (T), cytosine (C ), and guanine (G).

In the molecule these bases are holding together to the two helixes. They're held together by the following paired bases:

Adenine and Thymine

Guanine and Cytosine

They are called base pairs (nitrogenous bases). They're always found in DNA. 

Notice that the bases on one side of Helix have specific order: A, C, T, G, A, A, C, C, A, G.The order create up a gene. 

Gene is inside the nucleus, so the gene is defined as order of bases (ATGC) and the number of the bases. Both of them are important information for the construction of protein in the cytoplasm. It also gives the characteristic.
DNA molecules can also copy itself, which copies the genetic code exactly. This is important because to an extent they must copy and divide itself --- mitosis.