Topic 3-Glossary Flashcards
Eukaryotes
Organisms whose cells contain their DNA inside a nucleus and have discrete membrane bound organelles.
Prokaryotes
Organisms whose cells do not contain their DNA within a nucleus, or other membrane bound cell organelles. The bacteria. Considered an earlier stage in the evolution of life than the eukaryotes.
Rough endoplasmic reticulum
Interconnected membrane-bound, flattened sacs found in the cytoplasm of eukaryotes, with ribosomes attached to the surface.
Smooth endoplasmic reticulum
As above but with no ribosomes attached, makes lipids and steroids.
Ribosomes
A small organelle composed of RNA and protein that is the site of protein synthesis
Mitochondria
Organelle with inner and outer membrane,inner membrane is folded to form cristae. Site of later stages of aerobic respiration.
Centrioles
A paired organelle that helps organise the microtubules in animal cells nuclear division. Hollow cylinders, formed by a ring of nine microtubules.
Lysosomes
Single membrane bound organelles which contain digestive enzymes. Involved in breakdown of unwanted cells/structures.
Nucleus
Double membrane bound organelle with several nuclear pores. Contain the chromosomes and the nucleolus.
Nucleolus
Dense body within the nucleus where the ribosomes are made.
Golgi apparatus
Flattened membrane bound sacs formed by fusion of vesicles from the ER. Plays a role in the production and release of secretory material e.g. digestive enzymes.
Protein trafficking
The process by which proteins are made to where they are needed, and/or secreted from the cell.
Peptidoglycan
Type of polysaccharide/polypeptide compound found in the prokaryotic cell wall.
Capsule
Slime layer surrounding the cell wall of some prokaryotes.
Pili
The protein tubes which allow bacteria to adhere to surfaces.
Flagellum
Rigid rotating helical-shaped tail like structure used for movement.
Gametes
The mature sexual reproductive cell, e.g. the egg or sperm.
Acrosome
Modified lysosome found at the forward tip of an animal sperm, contains enzymes which break down jelly-like coating of the ovum.
Fertilisation
Process where the gametes combine, and the nuclei fuse to form the zygote.
Zygote
Fertilised egg, in which the gamete nuclei are also fused. The earliest stage of the diploid generation.
Haploid
One copy of each chromosome, found in the gametes=n
Diploid
Two copies (homologise) of each chromosome =2n. Usually Aries as a result of the fusion of two gametes, each with just one copy of each chromosome.
Meiosis
Division of a diploid nucleus to produce four haploid daughter cells. The process consists of two successive divisions with only one cycle of chromosome replication.
Independent/random assortment
The random separation during meiosis of a non-homologous chromosomes; so that each homologous pair of chromosomes can pass independently of another homologous pair of chromosomes, into a gamete.
Crossing over
The breaking and random rejoining of chromatids during the first prophase of meiosis. It results in the arrangement of genetic material and is important source of genetic variation.
Chiasma/chiasmata
The visible manifestation of crossing over between homologous chromosomes. The point where the chromatids break and rejoin during the first prophase of meiosis.
Pollen tube
Tube formed from the germinating pollen grain when it lands in stigma. The tube grows down through the style.
Tube nucleus and generative
The pollen grain contains two nuclei.
Polar nuclei
The two polar nuclei in the embryo sac fuse with one of the male gametes to form a triploid cell. The triploid cell divides to form the endosperm.
Egg nucleus
One of the male gametes fuses with the egg nucleus to form the diploid zygote. The diploid zygote divides to form the embryo.
Radicle
Young root
Plumule
Young shoot
Cotyledons
Seed leaves- mono=1, di=2.
Endosperm
Storage tissue in the seed.
Testa
Seed coat
Fruit
Ovary will develop into this.
Mitosis
Cell division which produces two daughter cells each with a chromosome complement identical to that of the original cell.
Cell cycle
The controlled series of events where one cell divides to produce and another cell identical to the parent cell. Includes all the stages of interphase and mitosis.
Interphase
The period between successive nuclear divisions. Consists of the G1, S and G2 phases. Length of interphase may vary.
G1 phase
First gap phase between the end of mitosis and the onset of the S phase, most variable in length.
S phase
The stage of interphase during which DNA is replicated.
G2
Second gap phase, between the S phase and mitosis.
Prophase
The first stage of nuclear division during which the chromosomes become thicker and shorter to form chromatids, joined together by a centromere. The Spindle forms and the nuclear membrane breaks down.
Metaphase
The stage of nuclear division at which the chromosomes line up in one plane. The Centromeres are attached to spindle fibres.
Anaphase
The stage of nuclear division where the spindle fibres shorten, pulling chromatids to each pole. The spindle then breaks down.
Telophase
The final stage of nuclear division where the chromosomes become diffuse and the nuclear membrane reforms.
Chromatid
Each of a pair of sister chromosomes, from the time at which molecular duplication occurs until the time at which centromere separate at the anaphase of nuclear division.
Chromosome
In eukaryotes, a long strand of DNA that contains part of the genetic information of cells, in the form of many genes.
Centromere
The region where sister chromatids join.
Chromatin
The nuclei can acid-protein complex found in eukaryotic chromosomes.
Asexual reproduction
Reproduction without gametes
Blastocyst
Hollow ball of cells surrounding a central cavity,formed five days after conception.
Stem cells
Cells found in embryo, foetus and adult which can divide repeatedly throughout life and are unspecified. Given appropriate signals they can differentiate into many specialised cell types.
Differentiation
The process by which cells become specialised in terms of biochemistry and/or morphology.
Pluripotent
Can differentiate into most, but not all, of the 216 cell types.
Totipotent
Cells can divide to form a complete human being.
Multipotent
Can differentiate to form a small subset of cell types.
Cloning
The process where the nucleus from one cell of an animal is transplanted into an un-fertilised egg (nucleus previously removed). The diploid cell will produce an organism genetically identical to the organism from which the nucleus was used.
Therapeutic cloning
A procedure designed to provide cloned stem cells for a patient. The patient would donate diploid cells (e.g skin cells), the nucleus would be removed and inserted into an empty ovum producing a diploid cell (somatic cell nuclear transfer). This cell could be stimulated to divide to form blastocyst from which stem cells could be harvested.
cDNA
Complimentary DNA made using an RNA template and the enzyme reverse transcriptase.
Promoter
The region of DNA, upstream of the coding part of the gene, that acts as the initial biding site for the RNA polymerase.
Gene induction
The process where transcription and translation of a gene occurs and a protein is produced. This is what we mean when we say a gene has been “switched on”.
B-galactosidase
Enzyme found in bacteria which break down lactose to form glucose and galactose. Expression is normally prevented by a repress or binding to the operator sequence. Expression of this enzyme is induced when lactose is present.
Regulator protein
A protein which attaches to RNA polymerase and a promoter region - required for transcription to be initiated.
Repressor protein
Molecules (often proteins) which prevent transcription in a variety of ways, e.g. by binding to promoter region and blocking transcription.
Signal Proteins
Can be hormones, growth factors or other regulatory molecules which switch on gene transcription.
FOP- Fibrodysplasia ossificans progressiva
Rare condition where bone growth occurs in odd places. Caused by a mutation which means genes that cause bone growth are not switched off in white blood cells.
Tissue
A group of specialised cells working together to carry out one function.
Adhesion molecules
Cell surface recognition molecules which enable cells to recognise and attach to each other.
Organ
A group of tissues working together to carry out one function.
Master genes
Genes which switch on the expression of many other genes that control the development of large body segments.
Meristem
Area of undifferentiated plant cells where cell division will form specialised plant organs.
ABC genes
Three genes that determine which flowering structure will for from meristem.
Gene A expression results in a sepal formation.
Gene B expression results in carpel formation.
Gene A and B expression results in petal formation.
Gene B and C expression results in stamen formation.
Genotype
Genetic makeup of an organism.
Phenotype
The observable properties of an individual as they have developed under the combined influence of the genetic constitution of the individual and the effects of the environmental factors.
Continuous variation
Characteristics which can be measured on a continuous scale, e.g. height
Discontinuous variation
Discrete characteristics, e.g. male, female
Polygenic
Number of genes involved in the inheritance of the same characteristics.
Where several genetic and one or more environmental factors are involved the condition is said to be _____________________
Multifactorial
Melanin
Dark pigment in the skin, protects DNA from UV damage.
Melanin-stimulating hormone (MSH).
Hormone which induces gene expression in melanocytes to produce melanin. Binds to cell surface receptors.
Melanosome
Melanin is packaged into these vesicles and transferred to nearby skin cells.
Tyrosinase
Enzyme involved in the first step in the metabolic pathway that makes melanin, which changes tyrosinase to melanin. Albinos have mutated version of this enzyme.
MAOA Monoamine oxidase A
Enzyme which catalyses the breakdown of a neurotransmitter in the brain involved in regulation of behaviour.
Cancer
A disease caused when the rate of cell multiplication is faster than the rate of cell death of cell death.
Tumour
A disorganised mass of cells, often growing out of control. If malignant, may spread to other parts of the body.
Carcinogen
A substance that causes cancer.
Oncogenes
Genes which code for proteins that stimulate the cell cycle, stimulating the transition from one stage to the next.
Tumour suppressor genes
Genes which produce suppressor proteins that stop the cell cycle.
p53
A tumour suppressor gene which inhibits the CDKs at the G1/S transition and therefore stops the cell cycle.
BRCA1
A gene which normally produces a protein which repairs DNA. Mutated in some cases of breast cancer.
BRCA2
A second breast cancer gene, found on chromosome 13, which has a DNA repair function.
