Compendium 10 and 11

Why do we need proteins in the body? Select Three

What is the name of the process by which DNA is converted into mRNA and where does this event take place within the cell?

What is the name of the process by which RNA is converted into protein and where does this event take place within the cell?

What happens to DNA before the cell can divide? Why is this so important?

How and why does the cell package its DNA ready for division?

How and why does the cell package its DNA ready for division? - DNA [blank_start]condenses[blank_end] to form [blank_start]chromatin[blank_end], which then winds up to form [blank_start]chromosomes[blank_end]. Packaging the DNA in this way means it is [blank_start]protected[blank_end] during cell [blank_start]division[blank_end] and is easier to divide in half

What do the terms diploid and haploid mean? Give an example of a diploid cell and a haploid cell. - Diploid means a cell has the full amount of DNA e.g. all cells of the body except gametes - Haploid means a cell has half the amount of DNA e.g. gametes (sperm and egg)

- [blank_start]Diploid[blank_end] means a cell has the full amount of DNA e.g. all cells of the body except gametes - [blank_start]Haploid[blank_end] means a cell has half the amount of DNA e.g. gametes (sperm and egg)

Diploid means a cell has the full amount of DNA e.g. all cells of the body except gametes

Haploid means a cell has half the amount of DNA e.g. gametes (sperm and egg)

Why do gametes only have a haploid amount of DNA?

Number of chromosomes in human cells

Number of pairs of chromosomes

Number of pairs of autosomal chromosomes

Sex chromosomes in men are:

Sex chromosomes in women are:

Can you distinguish someone’s gender by seeing only their autosomal chromosomes in a karyotype?

What is a gene and what does it do?

What is an allele?

There are four characteristic functions of a cell: 1. Cell metabolism and energy use 2. Synthesis of molecules 3. Reproduction and inheritance 4. Communication

Proteins are all made from chains of amino acids. The sequence of amino acids is called the:

Amino acids all have different shapes, charges and side chains. This means proteins have different shapes - they are not just long straight chains of amino acids. This is because the amino acids interact with other amino acids in the chain in different ways, so proteins fold up into different shapes to form specific [blank_start]secondary and tertiary structures[blank_end]. If the mature protein involves more than one polypeptide chain twisted together, the protein is said to have [blank_start]quaternary structure[blank_end].

Secondary structure of proteins: The secondary structure of proteins results from hydrogen bonds (red dotted lines) that join the individual amino acids from the primary structure to form a pleated (folded) sheet or a helix (coil)

Secondary structure of proteins: The secondary structure of proteins results from [blank_start]hydrogen[blank_end] bonds (red dotted lines) that join the individual amino acids from the primary structure to form a pleated (folded) sheet or a helix (coil)

Collagen fibril (found in connective tissue) is made up of three polypeptide chains twisted around each other (Figure 11.4) and is called a fibrous protein.

What is the difference between a protein, a peptide and a polypeptide? [blank_start]Peptides[blank_end] are 2 or more amino acids [blank_start]Polypeptides[blank_end] are 10 - 50 amino acids long [blank_start]Proteins[blank_end] are > 50 amino acids long.

What is the relationship of DNA to proteins?

DNA carries the recipe for each protein. A gene is a segment of DNA that carries the instructions that specify the structure of a specific protein. The production of a protein, using the information stored in DNA, is called gene expression. Gene expression can be divided into two parts: 1. Transcription 2. Translation

Both DNA and RNA consist of the basic building blocks called nucleotides

Both DNA and RNA consist of the basic building blocks called [blank_start]nucleotides[blank_end]. Each nucleotide is composed of a [blank_start]sugar molecule[blank_end] (monosaccharide) to which a [blank_start]phosphate[blank_end] and nitrogenous base are attached.

How many nucleic acid bases code for one amino acid?

State the major role that each type of RNA plays during protein synthesis: [blank_start]Messenger RNA (mRNA)[blank_end] : takes the information from the genes (DNA) in the nucleus out to the ribosomes [blank_start]Transfer RNA (tRNA)[blank_end] : transfers amino acids from the cytoplasm to the ribosome and lines them up opposite their mRNA codon [blank_start]Ribosomal RNA (rRNA)[blank_end] : major structural component of the ribosome

DNA is a double-stranded molecule and consists of two stands – the coding strand and the template strand

Chromatid: • When a chromosome replicates ready for cell division, the two bits of replicated chromosomes that form are called chromatids. • Each of these chromatids is called a chromosome again when they separate and move into the daughter cells.

Homologous pair: • Chromosome pairs are called homologous pairs, each member of the pair is called a homologue. • One homologue is derived from your mother and one from your father. • Each chromosome in the pair codes for the same genes, so you have two versions of every gene, these are called alleles.

Cytokinesis • The division of cell organelles and cytoplasm. • Results in two identical daughter cells.

Unlike mitosis: the cell divides and pulls one of each pair of homologous chromosomes into each daughter cell (each chromosome still has two chromatids).

What is the purpose of the first meiotic division?

The Immune system is divided into two sections called:

The lymphatic system helps maintain fluid [blank_start]balance[blank_end], contributes to lipid absorption in the digestion system, and also plays an important role in immunity. Lymphatic vessels start as small dead-end tubes called lymphatic [blank_start]capillaries[blank_end], and are found near [blank_start]blood[blank_end] capillaries. When blood passes through blood capillaries, some of the fluid in the blood moves into the [blank_start]interstitial[blank_end] space in-between the cells. The fluid that moves out of the blood capillaries is high in [blank_start]oxygen and nutrients[blank_end], and as it surrounds the cells, this is how nutrient and gas [blank_start]exchange[blank_end] occurs. Most of this fluid eventually gets [blank_start]reabsorbed[blank_end] into the blood capillaries, but about 10% doesn’t and is instead absorbed by lymphatic capillaries.

The lymphatic capillaries are very [blank_start]permeable[blank_end] which means anything in the interstitial fluid can enter the lymphatic system. This includes bacteria or other foreign [blank_start]antigens[blank_end]. So if you have bacteria that have entered your body (e.g. through broken skin), the bacteria will enter the lymphatic [blank_start]capillaries[blank_end]. The lymphatic capillaries join together to form larger lymphatic [blank_start]vessels[blank_end]

Lymph nodes are round or oval shaped bodies found along [blank_start]lymphatic vessels[blank_end]. Fluid enters and leaves the lymph nodes via the lymph vessels. Lymph nodes contain [blank_start]macrophages[blank_end] (e.g. phagocytic cells) and [blank_start]lymphocytes (B and T cells)[blank_end]. As fluid passes through the lymph nodes it comes into contact with these [blank_start]immune cells[blank_end] and if there are bacteria etc. in the lymph they get trapped, [blank_start]recognised[blank_end] by the immune cells and an immune response will occur. Lymphatic vessels can also transport cancer cells that leave a primary tumour. This is why the “draining lymph nodes” of the region where a tumour is found are often checked to see if they contain cancer cells that have spread around the body. Lymph nodes are arranged in [blank_start]chains or clusters[blank_end], so lymph passes through one node after another increasing the chance that all pathogens will be recognised. Some places where there are many lymph nodes include the neck, under arms (axilla), thorax, and inguinal region.

If a pathogen breaches the physical barriers of the body, our next line of defence is an immediate, but non-specific (innate) response such as inflammation.

Cell-mediated responses: • Macrophages and other cells of the innate defences alert T cells that foreign antigens are present in the body. • In your body you have specific small populations of T cells that recognise different types of antigens. When the antigen is recognised by the specific T cell, the T cell will directly attack the infected cells and release chemicals that further promote innate immune responses e.g. inflammation and phagocytosis. • T cells also contribute to the activation of B cells (antibody mediated responses) • A small population of T cells remain after the infection is cleared – memory T cells. The memory T cells means the next time that particular strep bacteria enters Tom’s body he will be able to fight it off faster.

Antibody-mediated responses: • Once B cells are activated by the presence of the foreign antigen and with the help of T cells they differentiate into antibody releasing cells called plasma cells. • Antibodies have many ways of eliminating the antigen. You don’t need to know all of them, but a few examples are: - binding to the antigen to inactivate it - binding to several antigens together to form a “clump” of antigens and make them in effective. - when an antibody binds to an antigen, the complex is then often phagocytised by macrophages. • Like T cells, a small population of memory B cells remain after the infection is cleared and will help Tom fight off the strep infection faster next time.