Essentials of Genetics Chapter 2

Plasma membrane

an outer covering that defines the cell boundary and delimits the cell from its immediate external environment

cell wall

only in plants, composed to cellulose

glycocalyx

cell coat consisting of glycoproteins and polysaccharides that provide biochemical identity at the surface of cells, and the components of the coat that establish cellular identity are under genetic control

receptor molecules

act as recognition sites that transfer specific chemical signals across the cell membrane into the cell

Eukaryotic cells

the presence of a nucleus and other membranous organelles

Nucleus

houses DNA, which is complexed with an array of acidic and basic proteins into thin fibers

Chromatin

Clusters of DNA, RNA, and proteins in the nucleus of a cell

Chromosomes

condensed chromatin fibers

Nucleolus

Found inside the nucleus and produces ribosomes.

Prokaryotic cells

lack a nuclear envelope and membranous organelles

cytoplasm

a nonparticulate, colloidal material referred to as the cytosol, which surrounds and encompasses the cellular organelles

Endoplasmic reticulum

ER-- compartmentalizes the cytoplasm, greatly increasing the surface area available for biochemical synthesis. Smooth--site for synthesizing fatty acids and phospholipids, or rough--studded with ribosomes that translate mRNA into protein

Mitochondria

found in both animal and plant cells and create ATP. Has its own DNA and is able to duplicate itself and transcribe and translate their own genetic information.

Chloroplasts

found in plants, algae, and some protozoans--associated with photosynthesis.Has its own DNA and is able to duplicate itself and transcribe and translate their own genetic information.

Centrioles

Located in the centrosome, associated with the organization of spindle fibers that function in mitosis and meiosis; organize spindle fibers during early phases of mitosis and meiosis

Spindle fibers

play a role in he movement of chromosomes as the separate during cell division

Centromere

condensed or constricted region on a chromosome

Metacentric

centromere in the middle

submetacentric

between middle and end

Acrocentric

close to end

Telocentric

at end

Homologous chromosomes

chromosomes pairs exhibiting a specific length and centromere placement; identical in their genetic potential

karyotype

chromosome map

Sister chromatids

replicas of eachother

locus

gene site

Alleles

different alternative forms of the same gene

Sex-determining chromosomes

an exception to the concept of homologous pairs

Cytokinesis

cytoplasmic division

Kinetochore

an assembly of multilayered plates of proteins associated with the centromere

Nucleoid

vs

Nucleus

Nucleoid: A non-membrane-enclosed region in a prokaryotic cell where its DNA is located. It is typically present as a long circular DNA molecule that is compacted. and not associated very closely with proteins.

Nucleus: A membrane-bound structure that houses DNA in the form of chromatin.

What does the DNA sequence look like on a telomere?

TTAGG on one strand paird with AATCC on the other strand. One rection of telomere is a repeat made of six base pairs.

What is telomerase and what cells express this protein?

Telomerase is an enzyme in cells that is responsible for adding more repeat sequences for the end of the DNA, thus making the cells live longer. In germline cells, the telomerase is highly active permanently making the cells immortal (if they died out the human race wouldn't exist).

In normal somatic cells, telomerase decreases with increasing cell divisons, eventually leading to halted divisions.

The length of a species telomeres predicts the lifespan of that species. True or False?

False, lifespan has a lot more things tied into it, and we aren't sure if shortened telomeres cause old age /death or are a result of being old (like grey hair).

Which characteristics describe viral chromosomes?

They can be circular, linear, and made of nucleic acid molecule- either DNA or RNA- single or double-stranded.

Which of these characteristics describe bacterial chromosomes?

They tend to be circular, double stranded, and made of DNA.

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