BIO 120 midterm

cell

the basic structural and functional unit of all living organisms

nucleic acids

DNA and RNA

DNA

A complex molecule containing the genetic information that makes up the chromosomes.

RNA

single-stranded nucleic acid that contains the sugar ribose

fluorescence microscopy

fluorescent molecules absorb one particular wavelength of light and meat some of that absorbed light at another wavelength (black background)

confocal laser scanning microscopy

focusing a laser light source onto a very thin plane within either a naturally fluorescent specimen, or one treated with commercial fluorescent dyes. (3D image using computer)

Transmission Electron Microscopy

a beam of electrons is transmitted through an extremely thin section of a specimen (best resolution of internal organization of cells)

Scanning Electron Microscopy

a beam of electrons is scanned over the surface of a specimen resulting in a detailed 3D image. (intact specimens)

magnification

ratio of object as viewed to real size

resolution

minimum distance by which 2 points of the specimen can be separated and still be seen as 2 points

plasma membrane

A selectively-permeable phospholipid bilayer forming the boundary of the cells

bilayer

two layers

hydrophobic

Water fearing

cell wall

A rigid layer of nonliving material that surrounds the cells of plants and some other organisms.

glycocalyx

The external surface of a plasma membrane that is important for cell-to-cell communication

pilus

A short, thick hair-like protein structure that allows a bacterium to attach to other bacteria and surfaces.

gene

segments of DNA that code for specific proteins

cytosol

aqueous solution contining ions and various organic molecules

cytoplasm

A jellylike fluid inside the cell in which the organelles are suspended

organelle

small, organized structures important for cell function

cytoskeleton

a protein based framework for filament structures that helps maintain proper cell shape and plays key roles in cell division and chromosome segregation from cell generation to generation

microfilaments

Long, thin fibers that function in the movement and support of the cell

intermediate filaments

occur in parallel bundles and interlocked networks either alone or in combination with microtubules and/or microfilaments; provide structural support

microtubules

Spiral strands of protein molecules that form a tubelike structure

eukaryote

A cell that contains a nucleus and membrane bound organelles

prokaryote

A unicellular organism that lacks a nucleus and membrane bound organelles

nucleus

A part of the cell containing DNA and RNA and responsible for growth and reproduction

nucleoid

A dense region of DNA in a prokaryotic cell.

mRNA

A type of RNA, synthesized from DNA, that attaches to ribosomes in the cytoplasm and specifies the primary structure of a protein.

rRNA

type of RNA that combines with proteins to form ribosomes

ribosome

Cytoplasmic organelles at which proteins are synthesized.

ATP

(adenosine triphosphate) main energy source that cells use for most of their work

flagellum

a long cellular appendage specialized for locomotion

cilium

short cellular appendages that facilitate locomotion or function to sweep fluid over the surface of the cell

cell junctions

reinforce cell adhesions and provide avenues of communication

anchoring junctions

form button like spots or belts that run entirely around cells "webbing" adjacent cells together

tight junctions

regions of tight connections between membranes of adjacent cells

gap junctions

open direct channels that allow ions and small molecules to pass directly from one cell to another

plasmodesmata

channels through cell walls that connect the cytoplasms of adjacent cells

cell cycle

series of events that cells go through as they grow and divide

mitosis

division of a nucleus to produce 2 genetically identical daughter nuclei, each with the same complement of chromosomes

meiosis

a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores.

chromosome

a unit of genetic material composed of DNA and associated proteins, found in the nuclei of eukaryotic cells and in the nucleoid region of prokaryotic cells

ploidy

number of sets of chromosomes in a cell

haploid

having a single set of unpaired chromosomes

diploid

containing two complete sets of chromosomes, one from each parent.

chromatid

one half of a duplicated chromosome

sister chromatids

Replicated forms of a chromosome joined together by the centromere and eventually separated during mitosis or meiosis II.

chromosome segregation

separation of the sister chromatids during mitosis in which each new nucleus receives one copy of each chromosome

spindle

fanlike microtubule structure that helps separate the chromosomes during mitosis

centromere

Area where the chromatids of a chromosome are attached

centrosome

A structure in animal cells containing centrioles from which the spindle fibers develop.

kinetochore

A specialized region on the centromere that links each sister chromatid to the mitotic spindle.

cleavage furrow

The area of the cell membrane that pinches in and eventually separates the dividing cell

cell plate

A double membrane across the midline of a dividing plant cell, between which the new cell wall forms during cytokinesis.

binary fission

A form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size

origin of replication (ori)

DNA sequence at which helicase unwinds the DNA double helix and DNA polymerase binds to initiate DNA replication.

interphase

Cell grows, performs its normal functions, and prepares for division; consists of G1, S, and G2 phases

G1

Cell growth

S stage

DNA replication occurs

G2

Cell prepares to divide

G0

A nondividing state occupied by cells that have left the cell cycle, sometimes reversibly.

prophase

Chromosomes become visable, nuclear envelop dissolves, spindle forms

prometaphase

The second stage of mitosis, in which the nuclear envelope fragments and the spindle microtubules attach to the kinetochores of the chromosomes.

metaphase

Chromosomes line up in the middle of the cell

anaphase

Phase of mitosis in which the chromosomes separate and move to opposite ends of the cell

telophase

phase of mitosis in which the distinct individual chromosomes begin to spread out into a tangle of chromatin

cytokinesis

division of the cytoplasm

genetic recombination

new combination of genes produced by crossing over and independent assortment

homologous sequences

Sequences of organisms that have the same relation and structure due to shared origin, but not always the same function

gametes

reproductive cells

sexual reproduction

A reproductive process that involves two parents that combine their genetic material to produce a new organism, which differs from both parents

zygote

fertilized egg

fertilization

Fusion of an egg and sperm cell

homologous

term used to refer to chromosomes that each have a corresponding chromosome from the opposite-sex parent

sex chromosomes

X and Y chromosomes.

synaptonemal complex

A zipper-like protein structure that causes replicated homologs to become physically connected during prophase of meiosis I; sets the stage for crossing over.

crossing over

the exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring.

chiasmata

site of crossing over

homeostasis

A tendency to maintain a balanced or constant internal state; the regulation of any aspect of body chemistry, such as blood glucose, around a particular level

biotic

living

abiotic

Non-living

emergent properties

New properties that arise with each step upward in the hierarchy of life, owing to the arrangement and interactions of parts as complexity increases.

proteins

Chains of amino acids

lipids

Energy-rich organic compounds, such as fats, oils, and waxes, that are made of carbon, hydrogen, and oxygen.

carbohydrates

Broken down to glucose to provide energy.

Oparin-Haldane hypothesis

organic molecules, essential to the formation of life could have formed in the atmosphere of primordial earth (reducing atmosphere)

Miller-Urey Experiment

Experiment that found that organic molecules can form in a strongly reducing atmosphere.

ozone

protects us from uv rays; developed after oxygen levels in atmosphere began to increase

polymer

A long molecule consisting of many similar or identical monomers linked together.

monomer

A simple compound whose molecules can join together to form polymers

enzyme

A type of protein that speeds up a chemical reaction in a living thing

protobiont

abiotically produced organic molecules that were the evolutionary precursors of prokaryotic cells

liposome

an artificial lipid vesicle that can swell and contract depending on the osmotic conditions of their environment

transcription

synthesis of an RNA molecule from a DNA template

translation

Process by which mRNA is decoded and a protein is produced

ribozyme

catalyze reactions on a precursor RNA that led to their own synthesis

metabolism

the sum of all chemical processes that occur in an organism

oxidizing atmosphere

todays atmosphere; the presence of high levels of oxygen prevents complex, electron-rich molecules from being formed

reducing atmosphere

large concentrations of hydrogen, methane, and ammonia; primitive atmosphere