Notes, summaries, assignments, exams, and problems for Biology

Head and Neck Anatomy

Meninges and Sinuses

Falx Cerebri

Located between the two cerebral hemispheres.

Falx Cerebelli

Located between the two cerebellar hemispheres.

Tentorium Cerebelli

Located between the cerebrum and cerebellum.

Single Sinuses

• Superior sagittal sinus
• Inferior sagittal sinus
• Straight sinus
• Occipital sinus
• Basilar sinus

Paired Sinuses

• Sphenoparietal sinus
• Cavernous sinus
• Superior petrosal sinus
• Inferior petrosal sinus
• Transverse sinus
• Sigmoid sinus

Cavernous Sinus

Site: Sphenoid bone, extending to the superior orbital fissure.

Size: 2cm long, 1cm wide.

Structures within the Lumen:

• Internal carotid artery
• Abducent nerve

Structures in the Lateral Wall:

• Oculomotor nerve
• Trochlear nerve
• Ophthalmic nerve
• Maxillary nerve

Tributaries:

• Ophthalmic vein
• Superficial middle

Reverse Transcriptase

Production of DNA from RNA

Reverse transcriptase is an enzyme isolated from retroviruses that catalyzes the production of DNA from an RNA template.

Use in Molecular Biology

• Reverse transcriptase is used in recombinant DNA technology to produce genes for gene transfer.
• It catalyzes the production of complementary DNA (cDNA) from an mRNA template.
• cDNA does not contain introns because mRNA undergoes splicing before cDNA production.
• Bacteria lack the machinery for intron removal, so genes inserted into them need introns removed to produce functional proteins.
• Examples of reverse transcriptase use include:
  • Mass production of human insulin by E. coli.
  • Generation of cDNA libraries for DNA microarrays (DNA fingerprinting).

Gene Therapy

Somatic

Activites

1.) Difference between primary and secondary sex characteristics:

The primary are the sexual organs which are born with and the secondary are the physical characteristics developed during puberty

2.) Reproduction:

Is the creation of new individuals

3.) Explain the journey of sperm to the ovum:

After been secreted by the penis through the urethra, the sperm go from the vagina to the uterus, Then, they divide in 2 groups and go to each fallopian tube. If there’s an ovum, one of these single sperm will fertilize it, and they will form a zygote, divides and becomes a morula and later a blastocyst. On the 7 days, the blastocyst implants in the endometrium

4.)

Fertilization

Fertilization occurs when a sperm and an ovum unite, forming a zygote. This process requires both ovulation and sexual intercourse. It's only possible during a 24-48 hour window after ovulation, although sperm can survive up to 5 days inside the female reproductive tract. The sperm penetrates the ovum's covering, and a fertilizing membrane forms, preventing other sperm from entering. The nuclei of the sperm and ovum join. After fertilization, the zygote travels to the uterus. The corpus luteum continues to release progesterone, maintaining the thick endometrium walls and preventing menstruation. During its journey, the zygote divides, becoming a ball of cells called a morula (around day 4) and then a blastocyst (around day 5).... Continue reading "Understanding Human Reproduction and Infertility" »

Describe the location and Functions of the lateral occipital cortex (LOC), the fusiform face area (FFA) And the estrastriate body area (EAB).

The Lateral occipital complex (LOC) is a large region of the ventral stream of the Visual association cortex, and appears to respond to a wide variety of objects And shapes. // The fusiform face area (FFA) is located in the ventral stream, On the anterior fusiform gyrus. It recognizes facial features, but also the Activity of this region can be affected by previously learned information. // The Extraestriate body area (EBA) is located in the ventral stream posterior to the FFA and partly overlaps it. This region is specifically activated by Photographs, silhouettes, or stick drawings of human bodies or

Gas Exchange

Blood is circulated to the lungs to obtain oxygen. This happens in the alveoli. Air entering the lungs has a higher concentration of oxygen and a lower concentration of carbon dioxide than the air that the lungs release. The blood exiting the lungs has a higher oxygen concentration and a lower carbon dioxide concentration than when it enters. The amount of nitrogen remains constant. Oxygen passes through the alveolar wall. These gases traverse the membrane of the cells by diffusion.

What Happens Inside the Alveoli?

The total surface area of the lungs' alveoli is enormous. Each alveolus is surrounded by many tiny blood vessels called capillaries, and the wall is extremely thin.

Microorganisms in the Air

Upper respiratory illnesses like... Continue reading "Human Biology: Respiration, Microorganisms, and Nutrition" »

The Endocrine System

The endocrine is made up of coordinated groups of glands called endocrine glands. They are called endocrine because they release hormones into the bloodstream.

Hormones

Hormones are chemical messengers that activate or stop, accelerate or delay many processes carried out by organs and tissues.

Health Diet (E.S)

Healthy diet, regulate moderate-intensity exercise, and don't consume drugs.

Health Diet

Healthy diet, exercise regularly, and practice correct postures.

The Control of Hormone Secretion

Feedback mechanisms in the endocrine system act similarly. When the amount of hormone in the blood reaches a specific level, a signal makes the gland stop releasing it.

How Hormones Work:

1. Stimulated endocrine glands respond by producing hormones

Stages of Cell Division

Prophase: The first stage of cell division, before metaphase, during which the chromosomes become visible as paired chromatids and the nuclear envelope disappears. The first prophase of meiosis includes the reduction division.

Metaphase: The second stage of cell division, between prophase and anaphase, during which the chromosomes become attached to the spindle fibers.

Anaphase: The stage of meiotic or mitotic cell division in which the chromosomes move away from one another to opposite poles of the spindle.

Telophase: The final phase of cell division, between anaphase and interphase, in which the chromatids or chromosomes move to opposite ends of the cell and two nuclei are formed.

Cytokinesis: The cytoplasmic division of... Continue reading "Cell Division, Reproduction, and Biological Processes" »

Genetics Terminology

Basic Concepts

• Trait: An inheritable characteristic of an organism.
• Gene: A DNA segment containing information that controls a specific trait.
• Allele: A variant form of a gene, often arising from mutations, contributing to hereditary variations.
• Locus (pl. Loci): The specific location of a gene on a chromosome.

Zygosity

• Homozygous Organism: Possesses identical alleles for a given gene (e.g., AA or aa).
• Heterozygous Organism: Possesses different alleles for a given gene (e.g., Aa).

Allele Interactions

• Dominant Allele: An allele that expresses its phenotype regardless of the paired allele.
• Recessive Allele: An allele that expresses its phenotype only when paired with an identical allele.

Genetic Inheritance Patterns

• Dominance (Dominant