Understand the relationship between cells, nuclei,
chromosomes, genes, alleles and DNA.
Understand the role DNA plays in carrying
instructions to the next generation and determining phenotype.
Think, pair and share what do you know about DNA,
genes, chromosomes,
cells, nucleus,
organisms and can you put them in order of
magnitude?
What are we made of?
Organisms are made of cells, each cell contains a nucleus, the
nucleus contains chromosomes made up of DNA, and DNA contains many
genes.
Cells
All organisms on Earth are made of one or more cells
Nucleus
Inside each cell is a nucleus. The nucleus holds genome of the cell
in the form of chromosomes.
Chromosomes
Chromosomes are located inside the nucleus and are made up of long
chains of DNA. Humans have 23 pairs of chromosomes, giving us 46 in
total!
Deoxyribonucleic Acid (DNA)
DNA is a very long chain of base pairs which forms
chromosomes.
Genes
A gene is a small segment of DNA made of base pairs and are
what determine everything about us! Each chromosome carries
many genes. Humans have around 25000 genes. That is a
lot of genes per chromosome!
Alleles
Each gene has two alleles, one
allele comes from each parent. E.g. brown hair from
mum, blonde from dad.
Mahi Tuatahi: Review!
Discuss with the people around you and create a diagram relating
cells, nuclei, DNA, chromosomes, DNA and alleles to each other. Try and
do it without using your notes (but look if you need to!).
Allele
A gene has two alleles: one from each parent. The allele is on a
chromosome and we call two chromosomes of the same shape a
homologous pair.
Homozygous and Heterozygous
If you have two of the same allele (e.g. brown and brown) this is
homozygous. If you have different alleles (e.g. brown and blue)
this is heterozygous.
Structure of DNA
Structure of DNA
We call this complementary base
pairing.
Which bases pair with which bases and what are they
called? Label them on your diagram!
Questions
Answer question 1 and 2 on page 9 of your sciPAD.
Exercise: Building DNA!
on sciPAD pages 8-9, cut out the DNA pieces and build some DNA and
stick it on the previous page!
