SQA Biology Flashcards

Flashcards for the entire document provided

Division and differentiation in human cells

Division of somatic and germline cells. Somatic stem cells divide by mitosis to form more somatic cells. Germline stem cells divide by mitosis and by meiosis.

Cellular differentiation

The process by which a cell expresses certain genes to produce proteins characteristic for that type of cell, allowing the cell to carry out specialised functions.

Therapeutic and research uses of stem cells

Used in repair of damaged or diseased organs or tissues. Stem cells are used as model cells to study how diseases develop or being used for drug testing.

Cancer cells

Divide excessively because they do not respond to regulatory signals, resulting in a mass of abnormal cells called a tumour. They may fail to attach to each other, spreading through the body where they may form secondary tumours.

Structure of DNA

Nucleotides (deoxyribose sugar, phosphate and base), sugar–phosphate backbone, base pairing (adenine–thymine and guanine–cytosine) by hydrogen bonds and double stranded antiparallel structure, with deoxyribose and phosphate at 3’ and 5’ ends of each strand respectively, forming a double helix.

Polymerase chain reaction (PCR)

Amplifies DNA using complementary primers for specific target sequences. Repeated cycles of heating and cooling amplify the target region of DNA.

Transfer RNA (tRNA)

Each tRNA molecule carries its specific amino acid to the ribosome.

Ribosomal RNA (rRNA)

Form the ribosome along with proteins.

RNA Splicing

The introns of the primary transcript are non-coding regions and are removed. The exons are coding regions and are joined together to form the mature transcript.

Mutations

Changes in the DNA that can result in no protein or an altered protein being synthesised.

Single gene mutations

Involve the alteration of a DNA nucleotide sequence as a result of the substitution, insertion or deletion of nucleotides.

Chromosome structure mutations

Duplication, deletion, inversion and translocation.

Genome

Is an organism's entire hereditary information encoded in DNA, made up of genes and other DNA sequences that do not code for proteins. In genomic sequencing the sequence of nucleotide bases can be determined for individual genes and entire genomes.

Pharmacogenetics and personalised medicine

Is the use of genome information in the choice of drugs. An individual’s personal genome sequence can be used to select the most effective drugs and dosage to treat their disease (personalised medicine).

Metabolic pathways

Integrated and controlled pathways of enzyme-catalysed reactions within a cell. Metabolic pathways can have reversible steps, irreversible steps and alternative routes.

Anabolic reactions

Build up large molecules from small molecules and require energy.

Catabolic reactions

Break down large molecules into smaller molecules and release energy.

Glycolysis

Is the breakdown of glucose to pyruvate in the cytoplasm.

Slow-twitch muscle fibres

Is a type of muscle fibre that contract relatively slowly, but can sustain contractions for longer. They are useful for endurance activities such as long-distance running, cycling or cross- country skiing.

Gamete production in the testes

Testes produce sperm in the seminiferous tubules and testosterone in the interstitial cells. The prostate gland and seminal vesicles secrete fluids that maintain the mobility and viability of the sperm.

Gamete production in the ovaries

Ovaries contain immature ova in various stages of development. Each ovum is surrounded by a follicle that protects the developing ovum and secretes hormones.

Fertilisation

Mature ova are released into the oviduct where they may be fertilised by sperm to form a zygote.

Menstrual cycle

The menstrual cycle takes approximately 28 days with the first day of menstruation regarded as day one of the cycle.

Stimulating ovulation

Ovulation is stimulated by drugs that prevent the negative feedback effect of oestrogen on FSH secretion. Other ovulatory drugs mimic the action of FSH and LH.

Antenatal screening

Antenatal screening identifies the risk of a disorder so that further tests and a prenatal diagnosis can be offered.

Dating scans

Measure pregnancy stage and due date and are used with tests for marker chemicals which vary normally during pregnancy.

Anomaly scans

May detect serious physical abnormalities in the fetus.

Blood circulation

Arteries, capillaries, then to the veins and back to the heart. There is a decrease in blood pressure as blood moves away from the heart.

Pressure filtration

Causes plasma to pass through capillary walls into the tissue fluid surrounding the cells.

Cardiac output

Is the volume of blood pumped through each ventricle per minute. Cardiac output is determined by heart rate and stroke volume.

Cardiac conducting system

The auto-rhythmic cells of the sino-atrial node (SAN) or pacemaker, located in the wall of the right atrium, set the rate at which the heart contracts.

Blood pressure

Hypertension (high blood pressure) is a major risk factor for many diseases including coronary heart disease.

Atherosclerosis

Is the accumulation of fatty material (consisting mainly of cholesterol, fibrous material and calcium) forming an atheroma or plaque beneath the endothelium

Thrombosis

The formation of a clot (thrombus).

Peripheral vascular disease

Narrowing of the arteries due to atherosclerosis of arteries other than those of the heart or brain.

High density lipoproteins (HDL)

These transport excess cholesterol from the body cells to the liver for elimination.

Low density lipoproteins (LDL)

Transport cholesterol to body cells.

Glucose tolerance test

Test is used to diagnose diabetes.

Obesity

A major risk factor for cardiovascular disease and type 2 diabetes. Obesity is characterised by excess body fat in relation to lean body tissue such as muscle.

Central nervous system (CNS)

Consists of the brain and the spinal cord.

Peripheral nervous system (PNS)

The somatic nervous system contains sensory and motor neurons.The autonomic nervous system (ANS) consists of the sympathetic and parasympathetic systems.

Converging neural pathway

In a converging neural pathway, impulses from several neurons travel to one neuron.

Diverging neural pathway

In a diverging neural pathway, impulses from one neuron travel to several neurons so affecting more than one destination at the same time.

Reverberating pathway

In a reverberating pathway, neurons later in the pathway link with earlier neurons, sending the impulse back through the pathway.

Cerebral cortex

Is the centre of conscious thought. It also recalls memories and alters behaviour in the light of experience.

Memory

Involves encoding storage and retrieval of information.

Sensory memory

Retains all the visual and auditory input received for a few seconds.

Short-term memory (STM)

Has a limited capacity and holds information for a short time. The capacity of STM can be improved by ‘chunking’ .

Long-term memory (LTM)

Has an unlimited capacity and holds information for a long time. The transfer of information from STM to LTM by rehearsal, organisation and elaboration.

Agonists

Are chemicals that bind to and stimulate specific receptors mimicking the action of a neurotransmitter at a synapse.

Antagonists

Are chemicals that bind to specific receptors blocking the action of a neurotransmitter at a synapse.

Adjuvant

Antigens are usually mixed with this when producing the vaccine to make the vaccine more effective and enhance the immune response.

Herd immunity

Occurs when a large percentage of a population is immunised. Establishing herd immunity is important in reducing the spread of diseases.

Independent variable

The variable that is changed in a scientific experiment.

Validity

All variables except the independent variable are controlled so it can be concluded that the effect is due to the independent variable.

Dependent variable

The variable that is measured to give results in a scientific experiment.