Science 9 Unit 1

Sustainability

Ability of the environment and living things it supports to endure into the future.

Reproduction

The production of offspring (sexual or asexual).

Continuity

How each species of organism continues to exist over time.

Asexual reproduction

Reproduction that needs only 1 parent and produces genetically identical offspring.

Sexual reproduction

Reproduction that needs 2 parents and produces genetically different offspring.

DNA (Deoxyribonucleic acid)

Stores genetic information of an organism.

Structure of DNA

Two long strands shaped like a twisted ladder containing 4 kinds of chemical building blocks called nucleotides.

Binary fission

Type of asexual reproduction where a parent cell splits into two separate, identical cells, called daughter cells.

Cell cycle

The process by which all eukaryotic cells reproduce.

Mitosis

The process of cell division that includes stages: Interphase, Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis.

Cytokinesis

The division of the cytoplasm and organelles to form two separate cells.

Meiosis

The process that turns diploid cells into haploid cells for reproduction.

Gamete

A haploid cell that is involved in sexual reproduction.

Diploid

A cell that contains two complete sets of chromosomes, one from each parent (46 chromosomes in humans).

Haploid

A cell that contains one complete set of chromosomes (23 chromosomes in humans).

Fertilization

The process that occurs when male sperm cells combine with female egg cells.

Homologous pair

A pair of chromosomes that carry almost identical information, one from each parent.

Crossing over

The exchange of genetic material between homologous chromosomes during Prophase I of meiosis.

Independent assortment

The random arrangement of chromosome pairs during Metaphase I of meiosis.

Asexual reproduction advantages

Only 1 parent is needed, reproduction occurs fast, offspring are genetically identical to the parent.

Asexual reproduction disadvantages

Lack of genetic diversity, vulnerable to changes in environment.

Sexual reproduction advantages

Genetic variation/diversity, allows some individuals to survive if environment changes.

Sexual reproduction disadvantages

Searching for a mate takes time, fewer offspring are produced, takes longer to grow and reproduce.

Yeast reproduction

Yeast cell grows a bud that pinches off to become its own cell.

Mould reproduction

Moulds form spores that are genetically identical to the cells they come from.

Plant reproduction

Plants can reproduce sexually and asexually, with asexual reproduction involving vegetative propagation.

Interphase

DNA is replicated. Organelles are replicated. Cell grows. Cell prepares to divide.

Telophase II

Four nuclei form. Cell prepares to divide

Prophase I

Nuclear membrane disappears. DNA condenses into chromosomes. Homologous chromosomes pair up. Crossing over occurs (exchanges genetic material)

Metaphase I

Spindle fibers attach to chromosomes. Chromosomes line up along the middle of the cell. Independent assortment occurs (the pairs line up randomly resulting in a random combination of chromosomes in each gamete cell

Anaphase I

Homologous chromosomes separate and move to each end of the cell

Telophase I

2 nuclei form. Each nucleus contains a complete copy of the cell’s DNA. Cell is ready to divide

Cytokinesis

Cell divides into 2

Anaphase II

Duplicate chromosomes are pulled apart and one copy moves to the end of the cell

Metaphase II

Chromosomes line up single file along the middle of the cell

Prophase II

Nuclear membranes disappear

What are genes?

Genes are a segment of DNA that contains instructions for building proteins and determining traits.

Where are genes located?

In a cell’s nucleus, specifically in chromosomes.

What is the job of genes?

To create proteins and determine features.

How do sustainability, continuity and reproduction relate to each other?

It is a cycle that repeats. Sustainability ensures that species can thrive over generations, while continuity through reproduction allows for the ongoing survival and adaptation of a species.

What is the function of DNA?

DNA is the “cell of life.” It stores the genetic information of an organism. Genetic information determines inherited traits of an organism.

Describe the specific arrangement of DNA pairs.

The 4 nucleotide bases (A) adenine, (T) thymine, (C) cytosine, and (G) guanine, pair specifically as A-T and C-G, forming the double helix structure.

True or false: the arrangement of nucleotides is NOT in the DNA molecule.

False; the arrangement of nucleotides is essential in the DNA molecule, as it contains genetic information.

List a cell in your body and how long it would take to repair.

Our skin cells take 2-4 weeks to repair.

Why is DNA replication important?

It allows the daughter cells to contain the same genetic information/DNA as the parent(s).

What is the end result of DNA replication?

Two strands of DNA, that contains one new and one old chain of nucleotides.

What is the end result of mitosis?

Two identical daughter cells.

As the nucleus prepared to divide, what happens to the DNA molecules that replicated during interphase?

The DNA condenses into chromosomes.

What are the two major processes that lead to genetic diversity in Meiosis?

Crossing over (prophase I) and independant assortment (metaphase I and anaphase I)