chapter 3 - heredity, cell biology and evolution

Cells

The building blocks of life that makes up all living things and is where all metabolic processes associated with life occurs

Cell history

All cells come from pre existing cells through division

• they carry hereditary material that gets passed onto new cells after division

4 main components of eukaryotic cells and what they are

Cell membrane - holds goop inside

Organelles - carry’s out cells vital functions

Cytosol - the goop

Nucleus - stores DNA

6 types of cells

1. Nerve

2. Muscle

3. Bone

4. Gland

5. Blood

6. Reproductive

DNa strcuture

• Double helix molecule of two chains that form a ladder

• Nucleotides link the chain

• 4 bases (ATCG) are used to write the genetic code

3 components of nucleotide

1. Deoxyribose sugar

2. Phosphate salt

3. Nitrogenous base

Gene

List of amino acid required to build a specific protein made of a chain of amino acids formed by codons

How do organisms grow and reproduce

Cells have a complete copy of its genetic code and uses it to divide then replicate itself

• they use base pairings to exactly copy without creating mistakes

2 instances of DNA replication

1. Growth and repair (mitosis)

• DNA replicates everytime a cell divides to help grow multicellular organisims

2. Reproduction (meiosis)

• sex cells have half as many chromosomes and pass it onto their offspring

Chromosome

Coiled up DNA molecule

How many chromosomes do humans have

46 chromosomes, one from each parent in pairs

Crossing over

Homologus chromosomes exchange portions with each other to reduce genetic linkage and make sure every daughter cell is unique

• occurs in prophase 1

Differences of mitosis and meiosis

Mitosis

• one division

• 2 identical daughter cells

• 46 chromosomes (diploid)

• Produces somatic cells

Meiosis

• 2 divisions

• 4 unique daughter cells

• 23 chromosomes (haploid)

• Produces sex cells

Mendals pea plants

Conducted hybrid experiments to study inheritance

• noticed that plants produced discrete traits with no blending

What did we learn from mendals pea plants

• Traits are controlled by genes with 2 different alleles

• The expressed allele in dominant, the hidden is recessive

• Genes occur in pairs, one from each parents and are found in homologus pairs

Genotype phenotype

G - genetic makeup

P - physical appearance determined by genotype

Gene locus

Location for a specific gene on a chromosome

Homozygous and heterozygous

Homo - 2 of same allele

Hetero - one dom one rec

Punnet square

Used to predict the possible genotype and phenotype of offspring if both genotype of parents are known

Principle of segregation

When individuals reproduce, alleles segregate and one gets passed to the offspring at random

• because this occurs for both parents, chromosome pairs are restored in fertilization