Photosynthesis, Cell Communication, Cell Division, and Meiosis

Comprehensive vocabulary flashcards covering photosynthesis experiments, cell communication types, cell cycle phases and disorders, and the mechanics of meiosis.

Photosynthesis

The process by which plants convert $CO_2$ and $H_2O$ into oxygen and glucose using light energy.

Chloroplast

The only light-absorbing devices in plants, serving as the site for photosynthesis.

Photosynthesis Reaction Formula

$$CO_2 + H_2O + \text{light energy} \rightarrow (CH_2O) + O_2$$

Jan Baptista van Helmont

Scientist (1577-1644) who conducted the Willow Tree Experiment and concluded that a plant's mass increase comes mainly from water, not soil.

Joseph Priestley

Scientist (1733-1804) who used the Candle and Plant Experiment to show that plants restore air, releasing a gas (later identified as oxygen) that supports burning.

Jan Ingenhousz

Scientist (1730-1799) who demonstrated through aquatic plant experiments that green plants produce oxygen only in the presence of light.

F.F. Blackman

Botanist (1866–1947) who concluded that photosynthesis is a multistage process, only one portion of which uses light directly.

Light-dependent Reactions

The stage of photosynthesis occurring in the thylakoid that uses light and $H_2O$ to produce $O_2$, ATP, and NADPH.

Calvin Cycle

The light-independent reaction occurring in the stroma that uses $CO_2$, ATP, and NADPH to produce $GA3P$.

Ligand

A signaling molecule that attaches to a receptor protein to initiate signal transduction.

Signal transduction

The process initiated when a ligand attaches to a receptor, allowing cells to influence one another.

Direct contact signaling

Communication where cells touch and signals are transmitted across gap junctions, such as in skin cells.

Paracrine signaling

Signaling that affects only cells in the immediate area, exemplified by a rotted potato influencing nearby potatoes.

Synaptic signaling

The transmission of neurotransmitters from nerve cells to target cells across a synaptic gap.

Endocrine signaling

Long-distance communication where signaling molecules are released into the bloodstream to reach target cells.

Autocrine signaling

A form of self-communication where a cell releases signals that bind to receptors on its own plasma membrane.

Binary fission

The method of cell division used by bacterial (prokaryotic) cells.

Interphase

The portion of the eukaryotic cell cycle consisting of the $G_1$, $S$, and $G_2$ phases.

M-phase

The phase of the cell cycle consisting of mitosis and cytokinesis.

S phase

The specific stage of interphase where DNA synthesis occurs.

$G_1$ Checkpoint

The restriction point in the cell cycle regulated by Cyclin D/CDK4 and Cyclin E/CDK2.

Cancer

A disorder of uncontrolled cell division caused by the failure of cell cycle regulation and checkpoints.

Nondisjunction

The failure of chromosomes to separate properly during meiosis or mitosis, leading to chromosomal disorders.

Aneuploidy

A condition of having an abnormal number of chromosomes, such as in Down syndrome (Trisomy 21) or Turner syndrome (Monosomy X).

Apoptosis

Programmed cell death; imbalances can lead to cancer (too little) or neurodegenerative diseases (too much).

Zygote

A diploid ($2n$) cell formed by the fertilization of a haploid sperm ($n$) and a haploid egg ($n$).

Synapsis

The process in Meiosis I where homologous chromosomes find each other and pair.

Genetic recombination

Also known as crossing over, this is the exchange of chromosomal information within the synaptonemal complex during Meiosis I.

Meiosis II

The second stage of meiotic division which resembles mitosis but occurs without DNA replication, resulting in 4 haploid sister cells.

Haploid ($n$)

The chromosome number found in gametes (sperm and egg) and the four daughter cells produced by meiosis.

Diploid ($2n$)

The chromosome number found in somatic (body) cells and the two identical daughter cells produced by mitosis.