BIOMOLECULES, CELLS. CELLULAR REPRODUCTION

Carbohydrates

Sugars and polymers of sugars, composed of a carbonyl (C=O) and hydroxide group (-OH)

Monosaccharide

Single carbon skeleton (e.g., glucose, galactose, fructose)

Disaccharide

Two monosaccharides linked by a glycosidic bond (e.g., maltose [glucose + glucose], sucrose [glucose + fructose])

Polysaccharide

Several linked monosaccharides (e.g., starch, glycogen, cellulose)

Lipids

Hydrophobic nonpolar hydrocarbon molecules

Unsaturated Fat

Contains a cis-double bond in the fatty acid, liquid at room temperature

Saturated Fat

No fatty acid double bonds, solid at room temperature

Trans Fat

Contains a trans-double bond in the fatty acid

Phospholipids

Lipids with a phosphate group attached to the glycerol, has a hydrophobic and hydrophilic end, compose the cell membrane

Steroids

Carbon skeleton is composed of four fused rings (e.g., cholesterol)

Proteins

Consist of one or more chains of amino acids

Amino acid

Consists of an amino group and carboxyl group; there are 20 kinds of amino acids

Nucleic Acids

Polymers of nucleotides (e.g., DNA and RNA)

Nucleotide

Contains a nitrogenous base (Purines or Pyrimidines), five-carbon sugar, and a phosphate group

Nucleus

Control center; houses genetic material

Ribosome

Free-floating or attached; site of protein synthesis

Smooth endoplasmic reticulum

Site of lipid synthesis and carbohydrate metabolism

Rough endoplasmic reticulum

Synthesizer of membranes and proteins; has attached ribosomes

Golgi apparatus

Modifier, sorter, and shipper of materials throughout the cell

Lysosome

Digests cellular materials

Vacuoles

Storage sac for water and nutrients

Mitochondrion

Site of cellular respiration

Chloroplast

Site of photosynthesis

Peroxisome

Producer of hydrogen peroxide and other enzymes involved in metabolic reactions

Cytoplasm

Gel-like substance that fills the cell; site of most biochemical reactions

Plasmodesmata

Pores between cell walls that allow intercellular communication

Cell membrane

Semi-permeable layer that surrounds the cytoplasm

Cell wall

Surrounds and protects the cell membrane

Passive transport

Adenosine triphosphate (ATP) is not required

Diffusion

Transfer of materials from a higher concentration to a lower concentration

Osmosis

Transfer of water towards the side of the membrane with a higher solute concentration

Active transport

use of ATP to move nutrients against a concentration gradient

Exocytosis

vesicles stick to the cell membrane and expel their contents

Endocytosis

molecules enter the cell through phagocytosis (cell eating) or pinocytosis (cell drinking)

Interphase

consists of G1, S, and G2 Phase

G1, G2-phase

cell growth and metabolism phase

S-phase

DNA synthesis phase that occurs between G1 and G2, duplication of chromosomes occurs

Mitotic Phase (M)

consists of Prophase, Prometaphase, Metaphase, Anaphase, and Telophase

Prophase

nucleolus disappears, mitotic spindle forms, duplicated chromosomes appear as sister chromatids, centrosomes move in opposite directions

Prometaphase

nuclear envelope disappears, chromosomes become condensed, sister chromatids captured by kinetochore microtubules, mitotic spindle attaches to kinetochore

Metaphase

centrosomes now at opposite sides of cell, chromosomes align at metaphase plate

Anaphase

sister chromatids break apart from each other, shortening of microtubules pulls chromatids toward opposite ends, cell elongates

Telophase

start of cytokinesis (C) and formation of cleavage furrow, nuclear envelopes and nucleolus form, chromosomes become less condensed, mitotic spindles disappear

Centrosome

contains material that functions in organizing mitotic spindles

Centromere

attachment point of two sister chromatids

Kinetochore

site of attachment of mitotic spindle to chromosomes

Meiosis

Haploid: N number of chromosomes, Diploid: 2N number of chromosomes, In humans, N = 23

Meiosis I

similar to mitosis, produces 2 diploid daughter cells

Meiosis II

occurs right after meiosis I, produces 2 haploid daughter cells each

Primary purposes of Mitosis

1. Asexual Reproduction - Mitosis is the method of reproduction of single-celled asexual organisms. 2. Growth - Mitosis is involved in cell reproduction, which results in increased cell number which adds more mass to the body. 3. Tissue Repair - Mitosis produces cells which replace damaged or dead cells.

Primary purposes of Meiosis

1. Sexual Reproduction - Meiosis of a single diploid germ cell involves DNA replication followed by two rounds of division, resulting in haploid cells called gametes. 2. Spermatogenesis - Immature sperm cells undergo successive cell divisions (spermatocytogenesis) and a change in cell form (spermiogenesis) to produce mature sperm cells (spermatozoa). 3. Oogenesis - The formation of the ovum or egg.