BIOLOGY KEY WORDS - TOPIC 3 (A LEVEL, EDEXCEL A SALTERS NUFFIELD)

BIOLOGY KEY WORDS - TOPIC 3 (A LEVEL, EDEXCEL A SALTERS NUFFIELD) (1) Cell Wall (definition, structure, function) - ANS-A rigid layer made out of polysaccharides -function: support and protection -Found in plant cells, bacteria and fungi (1) Centrioles (location, function) - ANS--Made up of microtubules that produce spindle fibres during mitosis (aids cell division) - Found in animal cells only - Located in cytoplasm, near the nucleus (1) Golgi Apparatus (where it's found, function) - ANS--Found in eukaryotic cells -Function: involved in the modification and packaging of proteins Lysosome (definition, function) - ANS-Membrane-bound vesicle that contains hydrolytic enzymes (Lysosyme) used for intracellular digestion (e.g. of foreign substances). (1) Mesosomes (where it's found, definition, function, ) - ANS--Found in bacteria -Used for respiration -Mesosomes form when the plasma membrane folds into the cytoplasm -> increases surface area -> helps carry out respiration efficiently. (1) Mitochondria (where it's found, function) - ANS--Found in eukaryotic cells -Site of aerobic respiration/generates energy in the form of ATP (1) Nuclear envelope (definition, structure) - ANS-A double membrane that surrounds the nucleus in the cell -has pores that allows substances to move in and out (1) Nucleolus (where it's found, function) - ANS--found inside the nucleus -synthesises ribosomes -contains proteins and RNA (1) Nucleus (where it's found, function) - ANS--Found in eukaryotic cells -Stores genetic information of the cell in the form of chromosomes -Surrounded by the nuclear envelope (1) Pili (where it's found, function) - ANS--Found on the outer surface of some bacteria -small hair-like projections -used to adhere to other cells (1) Plasmid (structure, where it's found) - ANS--Small, circular rings/loops of DNA -Located in the cytoplasm of many bacteria/prokaryotes (1) Ribosomes (where it's found, function) - ANS--Found in the cytoplasm/membrane bound organelles of both eukaryotic and prokaryotic cells. -Involved in protein synthesis (1) Rough Endoplasmic Reticulum - ANS--Membrane bound organelle -Involved in synthesis and packaging of proteins (1) Smooth Endoplasmic Reticulum - ANS--Membrane bound organelle -Involved in lipid synthesis (2) Sperm Cell (structure, function) - ANS--haploid -contains: flagellum, acrosome, mitochondria) -function: specialised for fertilisation of egg cell (2) Acrosome (where it's found, function) - ANS--organelle found at the head of the sperm cell -function: specialised to digest the outer coating of the egg cell during fertilisation (2) Zona Pellucida (structure, function) - ANS-A thick, transparent coating/membrane surrounding an ovum -Composed of glycoproteins -Prevents multiple sperms from fertilising the egg (sperm entering egg -> triggers cortical granules to signal ZP -> ZP hardens/thickens to become impermeable) (2) Locus (definition) - ANS-Location/position of a gene on a chromosome (2) Sex Linkage (definition) - ANS-refers to the allele that is located on a sex chromosome (X or Y) and codes for a trait that is related to gender. (2) Gene (definition) - ANS-A segment of DNA on a chromosome that codes for a specific trait, on a locus. (2) Meiosis (definition) - ANS-a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell. (2) Independent Assortment (definition) - ANS-formation of RANDOM combinations of chromosomes in meiosis and of genes on different pairs of HOMOLOGOUS chromosomes by the passage according to the laws of probability of one of each diploid pair of homologous chromosomes into each gamete independently of each other pair. (2) Homologous pairs (definition) - ANS--Two chromosomes that carry identical genes -diploid (2) Mitosis (definition) - ANS--a type of cell division that results in two daughter cells. -Cells produced are diploid (2) Asexual Reproduction (definition) - ANS-Producing genetically identical offspring from one parent through mitosis. (2) Process of fertilisation - ANS-Occurs when a sperm penetrates an ovum and the genetic materials fuse together to make a single cell called a zygote. -Processes: Acrosomal and Cortical reaction (2) acrosomal reaction (definition) - ANS-The process in which the sperm digests through the zona pellucida (using digestive enzymes from the acrosome (when acrosome fuses with sperm membrane)) and the egg membrane. This causes the sperm membrane to fuse with the egg membrane, allowing the sperm nucleus to enter the egg cytoplasm. (2) cortical reaction (definition) - ANS-The cortical reaction is when the sperm's nucleus enters the egg cytoplasm and they fertilise, causing the cortical granules (in the cytoplasm) to be released. The cortical granules being released causes the zona pellucida to thicken, preventing entry of more sperm. (3) Continuous Variation - ANS--a phenotypic characteristic that changes over a range of values (3) Differential gene expression - ANS-The expression of different sets of genes by cells with the same genome -It is the process by which genes are activated (or not) to express certain traits/functions. (3) DNA methylation - ANS--epigenetic modification of DNA the addition of methyl groups to bases in DNA, usually cytosine or guanine -Addition of methyl group prevents transcription (3) Epigenetics - ANS-the study of environmental influences on gene expression that don't involve changes in the DNA sequence. (3) Histone Acetylation - ANS-Epigenetic modification of histone proteins It is the process by which the acetyl group is added to the histone proteins, causing the DNA around the proteins to loosen and so allows for transcription. (3) Lac Operon - ANS-group of genes involved in lactose metabolism -regulated by the binding of the lac repressor (repressor enzyme) to the lac operon. (3) Operon - ANS-group of genes operating together (3) Organ - ANS-group of tissues that work together to perform closely related functions