Cells & Tissues

Question 1

Cytoskeleton

Answer 1

Microtubules: small tubular proteins which maintain cell structure and move organelles around the cell

Microfilaments: repeating units of actin, responsible for cell movement, changes in shape and make muscle contraction possible

Question 2

Centrioles

Answer 2

A pair of organelles that organise microtubules during cell division to create spindle fibres

Question 3

Cytoplasm

Answer 3

Viscous fluid containing proteins, other organic molecules and organelles

cytosol: where chemical reactions occur

Question 4

Golgi apparatus

Answer 4

modifies and packages proteins.

made of flattened sacs called cisternae

contains enzymes that allow processing and excretion of lipids and proteins

Question 5

Plasma membrane

Answer 5

a phospholipid bilayer that contains cholesterol, glycoproteins and glycolipids. it surrounds the cell and enables it to communicate and detect changes in the environment

Question 6

Mitochondria

Answer 6

site of aerobic respiration - produces ATP
the most active cells have lots of mitochondria

Question 7

What does catabolism mean

Answer 7

process of releasing energy

Question 8

Nucleus

Answer 8

DNA is stored
Nuclear envelope: double membrane that separates the contents of the nucleus from the cytoplasm

Nuclear pores: gaps in nuclear envelope

nucleolus: produces ribosomes

DNA is stored as chromatin, but during cell division the chromatin forms distinct structures called chromosomes

Question 9

Endoplasmic reticulum

Answer 9

RER: has ribosomes attached and is responsible for the synthesis of proteins

SER: synthesis and lipids and steroids. In muscle cells it releases calcium ions that trigger contraction

Question 10

Ribosomes

Answer 10

Protein synthesis - attaches amino acids using. Ribosomes are composed of two subunits containing rRNA

Question 11

Cilia

Answer 11

hairlike projections which allow movement of substances over the cell surface

Question 12

Phospholipids

Answer 12

Hydrophilic heads and hydrophobic tails

Question 13

What is the role of cholesterol in the plasma membrane?

Answer 13

stabilises the membrane

Question 14

What is the role of channel proteins in the plasma membrane?

Answer 14

let larger molecules in - such as polar molecules

Question 15

What is the role of receptor proteins in plasma membranes?

Answer 15

communicate with the environment outside the cell. molecules bind to them and a message is sent in. some have a carbohydrate molecule attached to them giving them immunological identity

Question 16

Examples of passive processes in cells

Answer 16

simple diffusion
osmosis
facilitated diffusion

these do not require ATP as molecules move from a high concentration to a low concentration

Question 17

Examples of active processes in cells

Answer 17

Active transport
Endo/exocytosis

these require ATP as molecules move from a low concentration to a high concentration

Question 18

Types of cells in connective tissue

Answer 18

Fibroblasts: make collagen and elastic fibres.
Fat cells
Macrophages: important in the body’s defence mechanism since they are phagocytic
Leukocytes: WBC - Migrate in large numbers during infection
Mast cells: histamine is responsible for inflammatory responses and heparin prevents coagulation

Question 19

What are mast cells?

Answer 19

WBC that play a role in the body’s immune system and inflammatory responses

Question 20

Examples of connective tissue

Answer 20

Elastic tissue: allows considerable extension and recoil
Fibrous tissue: closely packed collagen, found in ligaments, periosteum, protective coverings
Hyaline Cartilage: chondrocytes arranged in small groups within cell nests and the bluish white matrix is solid

Question 21

Where is epithelial tissue found?

Answer 21

covering surfaces, lining cavities, forms glands

Question 22

Simple epithelium

Answer 22

single layer of cells.

squamous epithelium: single layer of flattened cells, found in endocardium, alveoli and collecting ducts

Cuboidal epithelium: forms walls of kidney tubules and is found in the thyroid gland

Columnar epithelium: single layer of tall and thin cells on a basement membrane. Found in the stomach, small intestine and trachea

Question 23

Stratified epithelium overview

Answer 23

several layers of cells of various shapes
continual cell division in the lower layers pushes cells nearer to the surface. main function is to protect underlying structures from wear and tear.

Question 24

stratified squamous epithelium

Answer 24

in the deepest layers the cells are mainly columnar
keratinised: dry surfaces. no nuclei. provides tough and waterproof layer

non-keratinised: protects moist surfaces

Question 25

Transitional epithelium

Answer 25

pear shaped cells that allow stretching

present in the urinary tract

Question 26

Skeletal muscle

Answer 26

moves bones
striated and is under voluntary control
fibres are cylindrical and contain multiple nuclei

Question 27

Smooth muscle

Answer 27

non striated and involuntary
has lots of mitochondria
regulates the diameter of blood vessels

Question 28

Cardiac muscle

Answer 28

not under conscious control
striated
each fibre has one nucleus
intercalated discs are significant for heart contraction

Question 29

Types of nervous tissue

Answer 29

Excitable: neurones which initiate, receive, conduct and transmit info

non excitable: glial cells which support neurones

Question 30

3 types of membranes

Answer 30

Cutaneous
Mucous
Serous

Question 31

Mucous membranes

Answer 31

Lines hollow organs
lines the alimentary, respiratory and genitourinary tracts
epithelial cells secret mucus - which protects the membranes from drying

Question 32

Serous membranes

Answer 32

Closed cavities

double layer of loose areolar connective tissue lined by simple squamous epithelium

parietal = lines a cavity
Visceral = surrounds an organ

Question 33

cell cycle overview

Answer 33

Interphase: growth and replication

Prophase: chromatin condenses and becomes visible. spindle fibres form, centrioles go to opposite poles

Metaphase: chromosomes line up on the metaphase plate attached by their centromeres

Anaphase: centromeres become separated, one of each pair of chromatids migrate to each end of the cell. spindle fibres shorten

Telophase: spindle fibres disappear, chromosomes decondense, plasma membrane splits

Question 34

Apoptosis

Answer 34

genetically programmed cell death. shrinks and remaining fragments are phagocytosed without an inflammatory reaction

Question 35

Necrosis

Answer 35

Cell death as a result of lack of oxygen due to injury or pathological process

Question 36

Common causes of tumours

Answer 36

spontaneous changes in DNA or exposure to carcinogens such as: chemicals, ionising radiation and oncogenic viruses

Question 37

3 ways in which tumours can spread

Answer 37

Local spread: benign tumours grow and cause pressure damage

Lymphatic spread: group of tumour cells can break off and be carried to lymph nodes where they may lodge into secondary tumours, this may cause further spread into the lymphatic system because lymph drains into subclavian veins

Blood spread: thrombus may form, blocking blood vessels causing infarcts and the development of metastatic tumours

Question 38

Effects of tumours

Answer 38

Pressure effects: compression of adjacent structures can cause ischaemia, necrosis, blockage of ducts and pain

Hormonal effects: well differentiated tumours can secrete uncharacteristic hormones such as lung tumours secreting insulin

Cachexia: severe weight loss, weakness and lack of appetite

Question 39

Common causes of death in malignant disease

Answer 39

Infection: predisposition of infection is increased by prolonged immobility or bedrest and due to chemo or radioactivity

Organ failure

Carcinomatosis: widespread metastatic disease

Haemorrhage: Tumour ruptures