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

Genetic Code

• Each codon or triplet codes for a specific amino acid.
• It is degenerate: Amino acids can be coded by more than one codon or triplet (some triplets are synonyms). There are 64 codons for 20 amino acids.
• It is not ambiguous: Each codon encodes only one type of amino acid.
• It is universal: Apart from a few small exceptions.
• There are triplets that determine the beginning of translation ('start codon'): AUG (It codes for the amino acid methionine - Met).
• There are triplets that determine the end of translation ('termination' or 'stop' codons): UAA, UAG, UGA (They do not code for any amino acids).

Chromosomes

They are stick-shaped structures that arise from the condensation and packaging of chromatin during the division phases (mitosis and... Continue reading "Key Concepts: Genetic Code, Chromosomes, DNA, Cell Cycle" »

1)Which of the following best describes a karyotype?

·a display of each of the chromosomes of a single cell

2) The human X and Y chromosomes

·include genes that determine an individual's sex.

3) Which of the following is true of a species that has a chromosome number of 2n = 16?

·Each cell has eight homologous pairs.

4) In a human karyotype, chromosomes are arranged in 23 pairs. If we choose one of these pairs, such as pair 14, which of the following do the two chromosomes of the pair have in common?

·Length, centromere position, staining pattern, and traits coded for by their genes.

5) Meiosis II is similar to mitosis in that

·sister chromatids separate during anaphase

6) Which of the following occurs in meiosis but not in mitosis?

·synapsis of... Continue reading "Understanding Genetics: Karyotypes, Meiosis, and Inheritance" »

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

Reproduction:

Reproduction is the creation of new individuals

Explain the journey of sperm to the ovum:

After being secreted by the penis through the urethra, the sperm go from the vagina to the uterus. Then, they divide into 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, divide and become a morula and later a blastocyst. On the 7th day, the blastocyst implants in the endometrium

Structure:

NUMERO QUATTRO: HT Family History

Contains the health condition of parents (grandparents), siblings and children of the patient; no wife/husband. Have to note the occurrence of inheritable diseases: haemophilia, spherocytosis, DM, hypertension, cancer, “obesity”?. Draw family tree and mark affected people, we can localize if the disease is dominant, recessive and linked to sex chromosome X. Examination of chest.

INSPECTION:

SHAPE: Barrel chest (expiration prolonged, difficult), Pigeon breast (protruding breast bone, common in rickets), Funnel breast (inward deformity of sternum), Kyphoscoliosis (curvature of the spine, common in childhood rickets, can compromise ventilation), general deformities (due to chronic pulmonary and pleural diseases... Continue reading "Family History, Chest Examination, and Cardiac Diseases" »

Redi's Experiment
1668, Francesco Redi demonstrated that the maggots found in rotting meat came from fly’s eggs
1.     Redi placed pieces of meat in the same jars
2.     The first he left open, the second one he covered with some fabric and the third he covered with a cork
3.     The three jars were left in the same place and after a few days he saw that there were maggots in the first two jars but not the third one

Pasteur’s Experiment
Louis Pasteur demonstrated that microorganisms were not created from spontaneous generation.
1.     Pasteur placed meat soup in two flasks and bent their neck into an S-shape
2.     He sterilised the liquid by heating it and after two weeks saw that it didn’t decompose
3.     He

Vertebrata

Vertebrates are characterized by a backbone created from small parts called vertebrae and an endoskeleton. The endoskeleton can be made of:

• Cartilage (Cyclostomata, Chondrichthyes)
• Bones (Osteichthyes, Amphibians, Reptiles)

Key systems include:

• Central Nervous System: Brain, spinal cord, peripheral nerves forming a tubular nervous system.
• Vascular System: Closed, chambered heart.
• Breathing System: Gills, lungs.
• Excretory System: Kidneys.

They mostly have four limbs, although these are sometimes modified (e.g., fish fins, bird wings) or absent (e.g., snakes).

Cyclostomata (Jawless Fish)

These animals lived on Earth 500 million years ago. They live in shallow seas, mild climatic areas, and sometimes in fresh water. Their mouth opening is round;... Continue reading "Vertebrate Animal Groups and Features" »

Hyperadrenalism: