A Level Biology - Chapter 2 A

eukaryote

complex, multicellular, membrane bound organelles, 0.1mm animal, plant, agal, fungal

cell surface / plasma membrane

membrane found on surface of animal cells and inside the cell wall of other cells; regulates movement of substances in and out of cell

cytoplasm

fluid inside cell which metabolic reactions occur in

nucleus

large, nuclear envelope double membrane, pores, nucleolus, chromatin; contains genetic material and controls cell’s activity, pores allow RNA to move into cytoplasm

nucleolus

produces ribosomes

mitochondria

double membrane, inner membrane folded into cristae, matrix, respiratory enzymes; site of aerobic respiration

Golgi apparatus

a group of fluid filled membrane bound flattened sacs; processes and packages new proteins and lipids and produces lysosomes

Golgi vesicle

a small fluid filled membrane bound sac produced by the Golgi apparatus; stores processed lipids and proteins and transports them out of the cell

lysosome

round membrane bound organelle; contain digestive enzymes called lysozymes which digest invading cells or dead/broken components

ribosome

very small, attached to RER, 80s, made of proteins and RNA not surrounded by membrane; site of protein synthesis

rough endoplasmic reticulum - RER

large fluid filled membrane bound flattened sacs with ribosomes on surface; folds and processes proteins made at ribosomes, site of protein synthesis

smooth endoplasmic reticulum

large fluid filled membrane bound flattened sacs; synthesises and processes lipids

cell wall

rigid structure that surrounds plant cells, plant and algae cellulose, fungi chitin; supports cell structure and prevents cell changing shape

chloroplast

plant cells only, double membrane, matrix, starch granules, thylakoids stacked, grana linked by lamellae; site of photosynthesis

vacuole

membrane bound sac containing sap, tonoplast membrane; storage, maintains internal cell pressure to stay rigid and prevent wilting

epithelial cells

villi and microvilli increase surface area for absorption, lots of mitochondria for cotransport

red blood cells

no nucleus, biconcave, increase amount of oxygen that can be carried

sperm cells

lots of mitochondria for energy for movement towards egg

tissue

group of cells working together to perform a particular function

organ

different tissues working together

organ system

different organs working together

prokaryote

simple single celled organism, no membrane bound organelles, less than 2 micrometers

prok membranes

cell surface membrane and cell wall, cell wall made of murein glycoprotein

slime capsule

protect bacterium from attack by immune system cells

prok ribosomes

70s smaller than euk; site of protein synthesis

flagellum

long hairlike structure, rotates; moves bacteria

prok genetic material

free in cytoplasm, circular, not associated with histones, plasmids passed between prokaryotes

virus

acellular, capsid protein coat, attachment proteins, genetic core, replicate using host cell mechanisms

binary fission

DNA and plasmids replicate

cell expands DNA moves to opposite poles

cytoplasm divides new cell wall formed

two daughter cells, random assortment of plasmids

viral replication

virus attaches to receptor proteins, complimentary

genetic material released into host cell

gm replicated by host cell machinery

viral components assemble

new viruses released from host cell

magnification

how much bigger the image is compared to the specimen

magnification = size of image / size of real object

resolution

how well the microscope distinguishes between two close points

optical microscope

uses light, max magnification x1500, max resolution 0.2 micrometers

electron microscope

uses electrons, more detailed, max magnification x1500000, max resolution 0.0002 micrometers

transmission electron microscope TEM

electromagnets focus beam of electrons transmitted through specimen, denser absorb more electrons darker image, see internal structures, vacuum, thin, dead specimen

scanning electron microscope SEM

scan a beam of electrons across specimen, knocks off electrons from specimen collected to form image, 3D image, surface only, thick specimen, lower resolution

artefact

object visible down microscope that isn’t part of the specimen

cell fractionation

homogenisation break up membranes release organelles,

filtration through gauze remove large debris,

ultracentrifugation spin in centrifuge increasing speed, largest organelles separate first

drain supernatant and remove pellet

cell fractionation properties

ice cold reduce enzyme (lysozyme) activity, isotonic prevent cell lysis, pH buffer maintain pH prevent denaturing

mitosis

cell division of somatic cells, 2 genetically identical daughter cells

interphase

G1 growing, S DNA replication, G2 growing, normal cell function throughout

prophase

chromosomes condense, nuclear membrane break down, centrioles move to opposite poles

metaphase

chromosomes line up along equator, spindle fibres attach to centromere

anaphase

spindle fibres contract separating sister chromatids, pulled to opposite poles of the cell

telophase

chromatids uncoil, nuclear envelope reform around each pole

cytokinesis

cytoplasm divides producing two separate genetically identical daughter cells

mitotic index

mitotic index = number of cells with visible chromosomes / total number of cells visible