Using the key choices choose all responses that apply to the following descriptions. Some terms may be used more than once. Key:
a. stratum basale
b. stratum corneum
c. stratum granulosum
d. stratum lucidum
e. stratum spinosum
f. papillary layer
g. reticular layer
h. epidermis as a whole
i. dermis as a whole

1. layer of translucent cells in thick skin containing dead keratinocytes
2. two layers containing dead cells.
3. dermal layer responsible for fingeiprints.
4. epidermal layer exhibiting the most rapid cell division.
5. layer including scalelike dead cells, full of keratin, that constantly slough off.
6. layer named for the numerous granules present.
7. location of melanocytes and tactile epithelial cells.
8. area where weblike pre-keratin filaments first appear.
9. deep layer of the dermis
10. layer that secretes a glycolipid that prevents water loss from the skin

Answer and Explanation:

b. stratum corneum: 5. layer including scalelike dead cells, full of keratin, that constantly slough off.

The most superficial epidermal layer conformed of squamous, plane, thin cells with keratin in their cytoplasm, that are continuously released. These cells are replaced by new cells that have the same destiny.      

d. stratum lucidum

: 1. layer of translucent cells in thick skin containing dead keratinocytes

Also known as the transparent layer, is only located in the thicker parts of the skin, such as the hands´ palms and the feets´ soles. This layer is so thin that the cells´ edges and some ties their nucleus can not be identified. Keratinocytes are diaphanous and are grouped together. They lack a nucleus and the cytoplasm is filled with a gelatinous substance, eleidin, which will transform into keratin.

b. stratum corneum and d. stratum lucidum 2. two layers containing dead cells.

c. stratum granulosum: 6. layer named for the numerous granules present.

These layer cells contain granules filled with keratohyalin that is needed for keratin production. These cells are arranged in two to four layers, and they begin to degenerate. This is why they show high lysosomes enzymes concentration. This is also the layer where it begins keratinization.

e. stratum spinosum: 10. layer that secretes a glycolipid that prevents water loss from the skin.

8 to 10 irregular cell layers. These cells are rich in DNA necessary for proteinic synthesis that ends in keratin production, and Langerhans cells that belong to the immunity system. This stratus is also known as "Malpigio stratum". It also produces a glycoprotein that helps to prevent water loss.    

a. stratum basale 4. epidermal layer exhibiting the most rapid cell division.

                             7. location of melanocytes and tactile epithelial cells.

Stratum basale is the innermost germinative, single, basal layer of the epidermis composed of basal cuboidal-shaped cells. These cells are the precursor of keratinocytes, this is why this layer is also called germinativum. In this basal layer, there are also Merkel cells as well as melanocytes.  The former associated with nerve fibers, transmit part of the touch, and the latter, form the pigment responsible for skin coloring and tanning, melanin.

f. papillary layer: 3. dermal layer responsible for fingerprints.

This stratum is a thin superior layer in the dermis. It has conjunctive tissues and blood vessels that nourish the skin and helps to control the temperature. It´s surface forms papilla that increases the mechanical union between dermis and epidermis.        

g. reticular layer: 9. deep layer of the dermis

The inner and thicker layer of the dermis. It is characterized by it´s thick, irregular bundles of collagen fibers and elastic fibers. These are not randomly oriented but forming the regular skin tightening lines known as Langer lines.  

h. epidermis as a whole: 7. location of melanocytes and tactile epithelial cells.

Composed of a plane stratified keratinized epithelium that constantly grows and maintains a normal thickness by the process of peeling. The Epidermis is made up of five cell layers, which have different functions: Stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum.        

i. dermis as a whole:  composed of conjunctive dense tissue that provides support, resistance, and thickness to the skin.        

step 1: initiation

initiation is the beginning of transcription. it occurs when the enzyme rna polymerase binds to a region of a gene called the promoter. this signals the dna to unwind so the enzyme can ‘‘read’’ the bases in one of the dna strands. the enzyme is now ready to make a strand of mrna with a complementary sequence of bases.

step 2: elongation

elongation is the addition of nucleotides to the mrna strand. rna polymerase reads the unwound dna strand and builds the mrna molecule, using complementary base pairs. there is a brief time during this process when the newly formed rna is bound to the unwound dna. during this process, an adenine (a) in the dna binds to an uracil (u) in the rna.

step 3: termination

termination is the ending of transcription, and occurs when rna polymerase crosses a stop (termination) sequence in the gene. the mrna strand is complete, and it detaches from dna.

b. read the phase at the intersection of any given temperature and pressure.