Mendel to Mendeleev

Metals properties

shiny, malleable (bendy), ductile (stretched into wire), good conductor of heat and electricity, solid at room temp (except mercury)

Non-metals properties

dull, brittle, poor conductor, can be gas/liquid/solid at room temp

Ionic bond

the electrostatic attraction between a positive and negative ion

Polyatomic ion

an ion made of two or more atoms that carries an overall charge as one unit e.g. SO₄²⁻

Group 1

Alkali metals - Very reactive, soft, react violently with water

Group 2

Alkaline Earth metals - Reactive but less than Group 1

Groups 3-12

Transition metals - Hard, high melting point, less reactive, coloured compounds

Group 17

Halogens - Reactive, diatomic molecules F₂ Cl₂ Br₂ I₂, gas→liquid→solid down the group

Group 18

Noble gases - UNREACTIVE — already have full outer shell

Precipitation method

Identify ions in both solutions; Work out two NEW combinations; Check solubility table — X = precipitate (s)↓ No X = stays dissolved (aq)

Covalent structures

H₂O = H—O—H, Cl₂ = Cl—Cl, CO₂ = O=C=O, N₂ = N≡N

Lewis dot rule

Draw valence electrons as dots, shared electrons go BETWEEN the atoms, every atom needs a full outer shell (8 electrons, hydrogen needs 2)

DNA

the molecule that carries genetic information in all living things; Shape = double helix; Made of nucleotides (sugar + phosphate + base)

DNA bases

4 bases: Adenine, Thymine, Guanine, Cytosine; Base pairs: A always with T, G always with C; Found in the nucleus

Chromosome

a coiled strand of DNA; Humans have 46 (23 pairs)

Gene

a section of DNA that codes for a specific trait e.g. eye colour

Allele

a different version of the same gene

Dominant

an allele that always shows if present; Written as capital letter e.g. B

Recessive

an allele that only shows if you have TWO copies; Written as lowercase e.g. b

Genotype

the actual alleles an organism has e.g. BB, Bb or bb

Phenotype

what you can actually see e.g. brown eyes

Homozygous

both alleles are the same e.g. BB or bb

Heterozygous

the two alleles are different e.g. Bb

Haploid

a cell with half the number of chromosomes; 23 in humans, sperm and eggs

Diploid

a cell with the full number of chromosomes; 46 in humans, all body cells

Autosome

any chromosome that is NOT a sex chromosome; Chromosomes 1-22

Sex chromosome

the chromosomes that determine biological sex; XX = female, XY = male

Karyotype

a photo of all chromosomes in a cell arranged in pairs

Homologous chromosomes

a matching pair of chromosomes; One from mum, one from dad

Mitosis

cell division that produces 2 identical diploid daughter cells; Purpose = growth and repair of body cells; Phases in order = Prophase, Metaphase, Anaphase, Telophase (PMAT)

Meiosis

cell division that produces 4 non-identical haploid daughter cells; Purpose = make sex cells (gametes); Phases = PMAT twice, Meiosis I then Meiosis II

Asexual reproduction

reproduction requiring only ONE parent, offspring are identical clones

Binary fission

bacteria splits in two

Budding

bud grows off parent e.g. yeast

Fragmentation

breaks into pieces each grows e.g. starfish

Vegetative propagation

plants grow from roots or stems e.g. strawberry runners

Sexual reproduction

reproduction requiring TWO parents, offspring are genetically unique

Plants Male gamete

pollen, made in the ANTHER

Plants Female gamete

egg cell, in the OVULE inside the OVARY

Pollination

pollen moves from anther to stigma

Fertilisation (Plants)

pollen travels down style to reach ovule

Male part (Plants)

Stamen (anther + filament)

Female part (Plants)

Carpel (stigma + style + ovary)

Animals Male gamete

sperm, made in testes

Animals Female gamete

egg, made in ovaries

Fertilisation (Animals)

sperm + egg = zygote

Internal fertilisation

inside female body e.g. humans, dogs

External fertilisation

outside body in water e.g. fish, frogs

Gel electrophoresis

a technique that separates DNA fragments by size; DNA is negatively charged so moves toward POSITIVE end; Small fragments travel FURTHER; Matching bands in same position = same DNA