1. CYTOLOGY, GENETICS AND HISTOLOGY Flashcards
The characteristics of life. Different types of cells, organelles and tissues in the human body. DNA, RNA, gene structure, function and inheritance. Homeostasis, positive and negative feedback systems , movement of substances and protein synthesis.
Define ‘Homeostasis’
Homeostasis is the dynamic and ever-changing condition of equilibrium (balance) in the body’s internal environment maintained by the body’s own regulatory processes. It is a fundamental principle of physiology.
Differentiate the following terms by defining each:
- Anatomy
- Physiology
- Pathology
Anatomy is the study of structures that form the body.
Physiology is how the parts of the body work.
Pathology is the study of abnormalities from normal function.
Name four of the characteristics of ‘Life’
Metabolism - sum of all chemical processes
Responsiveness - ability to respond to changes in env.
Movement - cells, organs and whole organism
Reproduction - formation of new cells / organism
Growth - increase in size/number
Differentiation - development to specialised state
Vital Force/Qi - energy of life
Name four characteristics of ‘Death’
Loss of heartbeat.
Absence of breathing.
Loss of brain function.
No vital force/life force/Qi.
Name four of the physiological variables that must be kept within narrow parameters to enable homeostasis in the body
- Core temperature (36.5 - 37.5 degrees C)
- Water and electrolyte balance
- pH of body fluids
- Blood glucose levels (4-7mmol/L)
- Blood and tissue Oxygen/CO2 levels
- Blood pressure
- Flow of life force
Blood plasma, synovial fluid, lymph fluid and interstitial fluid are all examples of _____________ fluids
extracellular
Name the four body cavities
Cranial
Thoracic
Abdominal
Pelvic
Name four things that can cause oxidative damage in the body
Stress, smoking, toxins, diet high in refined foods and sugar
Define a negative feedback system and give one example
A negative feedback system is one where the output (from the effectors) reverses the input (detected by the receptors).
Examples are increasing or decreasing body temperature, blood glucose, blood pressure.
A positive feedback system strengthens/enhances change in one of the body’s controlled conditions, and is much rarer than negative feedback systems. Give three examples of positive feedback systems.
Blood clotting Childbirth Milk production Enzyme reactions Immunity
What are free radicals and how can they be countered in the body?
Free radicals are unstable and highly reactive molecules. They lack an electron in their atomic structure, which can be donated by antioxidants such as Vitamin A, C, E, beta-carotene (Vitamin A precursor), quercetin and lycopene.
What are the main differences between prokaryotic and eukaryotic cells?
Prokaryotic cells contain no nucleus and no membrane bound internal structures, while eukaryotic cells have both.
True or false:
Only prokaryotic cells have cell walls.
False: Plants and fungi are eukaryotes and their cells have cell walls.
Differentiate between ’cytosol’ and ‘cytoplasm’ by defining them.
Cytosol is the basic watery fluid inside a cell. Cytoplasm is the cell content excluding the nucleus (cytosol + organelles)
The cell membrane is a ________, semi-_________ membrane that separates the cell’s ________ and internal environment.
Flexible
Permeable
External
Briefly describe the structure of the cell membrane
The cell membrane is a phospholipid bilayer, these being arranged with the hydrophilic phosphate heads towards the outsides and the hydrophobic lipid tails on the inside.
Cell membranes are embedded with _____________ proteins and controls substance ________ in and out of cells.
Transmembrane
Movement
What are the functions of transmembrane proteins?
- Transport of substances in/out of cells (e.g. charged particles like hydrogen and larger molecules like glucose)
- Immunological identity: helps immune cells recognise our own cells
- Receptors: recognition sites for hormones etc.
Name two places in the body where tight cell junctions can be found
Stomach
Intestines
Bladder
Name five of the key organelles found in body cells
Nucleus (with nucleolus) Mitochondria Ribosomes Endoplasmic reticulum Golgi apparatus Lysosomes Cytoskeleton
All body cells have a nucleus with the exception of _____________________.
Red blood cells
The nucleus is a spherical structure that contains the body’s _______ information in the form of ___. It controls all cell functions, hence known as the _____ of the cell. It contains a _________, which produces RNA.
Genetic
DNA
Brain
Nucleolus
What organelle is continuous with the nuclear membrane?
Rough endoplasmic reticulum
DNA forms a double _____ which coils around proteins called ________.
Helix
Histones
How many chromosomes are there in somatic cells?
23 pairs (46)
How many chromosomes are there in gametes?
23
What are genes?
Sub-sections of DNA that act as instructions to make proteins.
Which heavy metal can cause damage to neurons, has been significantly linked to alzheimer’s and is a risk factor in cancers such as breast cancer?
Aluminium
A cell with 46 chromosomes (ie. 23 pairs), are termed _______, while cells with 23 chromosomes (gametes) are termed _______.
Diploid
Haploid
What is the complete set of chromosomes from a cell called?
Its karyotype
By which process do prokaryotic cells divide?
Binary fissure (rapid mitosis)
What is the definition of a hormone?
A chemical messenger that travels in the blood.
In the cells of which body cells are the most mitochondria found?
Liver, muscle and spermatozoa
Which type of cells in the body characteristically have gap junctions (small fluid-filled tunnels between neighbouring cells)
Nerve cells
Describe the structure of a chromosome
A chromosome consists of a pair of chromatids, joined by a centromere. A chromatid forms from chromatin that tightly coils itself around proteins called histones. These strands of tightly coiled DNA are double-stranded molecules, made up of two chains of nucleotides. Nucleotides consist of three subunits: a sugar, a phosphate group and a base. Likened to a twisted ladder, DNA’s uprights are formed by alternating chains of sugar (deoxyribose) and phosphate units. The four different bases bind to the phosphate in a precise order that makes up the genetic code.
Uncoiled, what length of DNA is there in each body cell?
2 metres (6 feet)
What is the cytoskeleton of the cell and what is its function?
The cytoskeleton is a network of protein filaments (microtubules and microfilaments) that extends throughout the cytosol that assists with:
- Generating cell movement- enable white blood cells to migrate to sites of injury and enable muscle contraction
- Physical support and shape of the cell
- Cell division - they move chromosomes apart (as the mitotic spindle)
What is the energy currency of the cell that is produced by mitochondria
ATP (adenosine triphosphate)
Finish the following ‘aerobic respiration’ equation:
Glucose + ______ = carbon dioxide + water + ___
Oxygen
ATP
What is the function of ribosomes in the cell and in which two places can they be found?
Ribosomes act as the site of protein synthesis (their name reflects their high content of ribonucleic acid). They are either mobile (free in cytoplasm - make proteins for use inside the cell) or stationary (bound to rough endoplasmic reticulum - make proteins for outside the cell).
What is the rough endoplasmic reticulum and what is its function?
It is a network of membranes in the form of flattened sacs that is continuous with the nuclear envelope, is studded with ribosomes and extends throughout the cytoplasm to the cell membrane. It synthesises and transports proteins out of the cell.
What is the role of the smooth endoplasmic reticulum?
It contains unique enzymes and
- synthesises lipids and steroid hormones (eg. oestrogen)
- In the liver it detoxifies alcohol and drugs
- In muscles, it releases calcium for muscle contraction.
What is the function of the Golgi apparatus in the cell?
The Golgi apparatus modifies, sorts, packages and transports proteins received from the rough ER. The membrane-bound vesicles of proteins created are stored, and when needed are moved to the plasma membrane before fusing with it and then expelling it from the cell in a process known as exocytosis. It can be likened to the cell’s Post Office.
What are lysosomes?
Lysosomes are small membranous vesicles that are pinched off from the Golgi apparatus. They contain as many as 60 powerful enzymes which engulf and digest fragments of organelles and large molecules (e.g. RNA, DNA, carbs and proteins) inside the cell that are either recycled or exported from the cell as waste material. Lysosomes in white blood cells digest foreign materials like microbes, and in sperm it releases enzymes externally to assist egg entry.
What kind of cells reproduce via mitosis and what is the end result?
Somatic cells reproduce via mitosis and each division creates two identical daughter cells.
Which body cells never undergo mitosis?
Neurons
How long does it take the following cells and organs to replace themselves:
- Skin
- Stomach and intestinal mucosa
- Liver
- Red blood cells
- Taste buds
- 40 days
- 5 days
- 5 months
- 90-120 days
- 10 days
Do gametes have a diploid or haploid nucleus?
haploid
What is the process called by which gametes reproduce?
Meiosis
Fertilisation describes the fusion of a ____ and a ______ gamete and leads to the formation of a ______, which undergoes mitosis and develops into an embryo and finally a ______ (after eight weeks).
male
female
zygote
foetus
Are mutations in somatic cells heritable?
No
Briefly outline the two phases of protein synthesis
- Transcription - a copy of one gene is made into mRNA which travels out of the nucleus to a ribosome
- Translation - the ribosome reads the code and produces a chain of amino acids to form the required protein.
What are the three types of passive transport
Substances always move from a high to low concentration:
- Diffusion - movement of small molecules (eg. gasses)
- Osmosis - passive movement of water
- Facilitated diffusion - movement of larger substances (eg. glucose and charged molecules) with the aid of transmembrane proteins
Active transport describes the movement of substances from an area of ____ to ____ concentration and requires ___. The main examples of active transport are:
- _____________
- _____________
- _____________
low
high
ATP
1. Pumps - e.g. sodium-potassium pump: use protein pumps in the cell membrane
2. Endocytosis - engulfing of particles into the cell through cell membrane extensions [phagocytosis and pinocytosis]
3. Exocytosis - removal of waste from the cell [vesicles engulf the material and fuses with the cell membrane before being expelled]
What are the four types of tissues found in the body.
- Epithelial tissue - closely packed cells e.g. epidermis, lining of lungs, digestive tract and heart
- Connective tissue - most abundant and diverse tissue e.g. bone, cartilage and blood
- Muscular tissue - contracts to create movement
- Nervous tissue - transmits electrical signals round the body
What are the two basic elements that connective tissue is made up from?
- Extracellular matrix: formed of ‘ground substance’ and ‘protein fibres’ (collagen and elastic)
- Cells: widely spaced, unlike epithelium. eg. fat cells and white blood cells
True or false: protein fibres produce fibroblasts
False: fibroblasts produce protein fibres
Where in the body is collagen fibres the most abundant?
Bone, ligaments and tendons
Describe the composition and function of elastic fibres
Elastic fibres are made from the protein elastin, surrounded by glycoprotein to add strength. It is strong but stretchy and allows tissues such as the skin, blood vessel walls and lung tissue to return to their original shape.
Name three types of connective tissue cells
Fibroblasts, Adipocytes and White blood cells (macrophages, lymphocytes and mast cells)
List five functions of connective tissue
- Structural (bone, cartilage)
- Transport (blood)
- Protection (bone, cartilage, adipose)
- Support and interconnection
- Insulation (adipose tissue)
- Energy store
- Production of blood and lymphatic cells (adipose, bone marrow)
- Defence and repair (blood, lymph)
Name four types of membranes in the body
- Cutaneous (skin)
- Mucous
- Serous
- Synovial
What is the role of goblet cells and where are they found?
Found in the epithelial layer of mucous membranes, goblet cells produce and secrete mucus which:
- Protects the membrane from mechanical and chemical injury / drying
- Traps foreign particles in the respiratory tract
Name the two layers of serous membranes
Visceral (inner) and Parietal (outer) layer with serous fluid between them [enables an organ to glide freely within the cavity without friction]
Name the three serous membranes found in the body
- Pericardium [surrounding heart]
- Pleura [lining thoracic cavity surrounding the lungs}
- Peritoneum [lining the abdominal cavity surrounding abdominal organs]
Where in the body can you find synovial membranes?
Synovial membranes line cavities of freely-movable joints and they contain synoviocytes which secretes synovial fluid which lubricates and nourishes the movable joint cavities which it bathes.
Define the term ‘mutation’
A mutation describes a heriditable change in the normal genetic make-up (DNA sequence) of a cell.
