Genetics Practical

Mitosis

The cell division process for somatic cells

Gametes

reproductive cells

Somatic Cells

non-reproductive cells

Meiosis

the cell division process for gametes

Division of the nucleus

mitosis

two daughter cells are identical to the original cell

mitosis

types of gametes in humans

spermatozoa and oocytes

4 daughter cells are produced

meiosis

gene

specific DNA sequences that codes for a specific protein

chromosomes

segments of DNA

loci

specific sites on DNA where genes are located

How many chromosome pairs do human somatic cells have?

23 homologous pairs or 46 chromosomes

Diploid

human cells with 46 chromosomes

Haploid

Gametes only have 23 chromosomes, 1 set of each chromocomes

Homologous pairs

same type of genes but may not be completely identical

alleles

different versions of same gene

allele inheiratnace

1 from each parent

homozygous

same allele for a gene on both homologues

heterozygous

different alleles for a gene

Dominant Alleles

always expressed

recessive alleles

only expressed if individual is homozygous for the recessive trait

phenotype

physical expression of a trait

genotype

combination of alleles that make up a phenotype

Interphase

regular cellular function and metabolism (not a real part of mitosis)

3 phases of interphase

G1, S, G2

G1 Phase

cell organelles doubled, materials from DNA synthesis materials generates

S Phase

DNA is replicated, at end each chromosome has an exact copy

Chromatids

duplicated chromosomes

centrome

where sister chromatids are joined

G2

proteins needed for cell division are synthesized, chromatids begin to condense

Prophase

beginning of mitosis

nuclear membrane breaks down and reabsorbed

miotic spindle apparatus is assembled either side of each centromere

chromatids fully condense

spindle finders extend to the centrioles located at opposite poles of the cell

Metaphase

chromatids line up at the metaphase plate

Anaphase

centrosomes divide

sister chromatids split

separated chromosomes now pull to the opposite polls

Telophase

chromosomes decondense

cellular function returns

end of mitosis

spindle apparatus dissembles

two new nuclei form at the poles

Cytokinesis

not a part of mitosis

parental cell splits into two identical daughter cells

animals cells —> cleavage furrow forms made of actin filaments between the two nuclei

slices through the cell

Interphase Meiosis

Same as mitosis

G1, S, G2

Prophase I

Miotic prophase same

homologous chromosome pairs are joined together by a synapsis

crossing over occurs random genes are exchanged between the paired chromosomes

sister chromatids are no longer identical

crossing over connection points are chiasmata

once the homologues separate from each other at the end of synapsis they remained connected at the chiasmata

spindle fibers only attach to one end of the centromere

Metaphase I

paired homologues line up at the midline of the cell

arrangement of homologues is random

no set pattern for maternal or paternal arrangement

Anaphase I

paired homologues are pulled apart

chiasmata is broken

one member of each pair is pulled to the opposite poles but centromeres are not split

sister chromatids in tact

Telophase I

new nuclei form around the chromatids

cytokinesis follows

two new haploid cells

Prophase II

short interphase - no dna rep

all prophase mitosis events occur

spindle fibers attach to both sides of centromere

metaphase II

chromatids line up at the midpoint of the cell

anaphase II

centromeres divide

sister chromatids pull apart to opposite sides

telophase II

new nuclei form at each pole

haploid

followed by cytokinesis

female meiosis

3 polar bodies

1 egg

male meiosis

4 haploid sperm cells — spermatozoa

Fertilization

haploid sperm fused with haploid egg

zygote produced

new combination of alleles

punnett sqaure

diagram used to determine offsprings genotype and phenotype

what is blood composed of?

plasma

red blood cells

white blood cells

platelets

plasma

clear, straw colored liquid that makes up 55% of the blood

percent of blood made up by formed elements, blood cells, cell fragments

45%

where are blood cells produced?

bone marrow

erthrocytes

red blood cells

most numerous cells in the blood

carry oxygen form lungs to all parts of the body

lack nuclei

hemoglobin

protein in rbcs

includes iron

combines w oxygen to travel through the lungs

leukocytes

white blood cells

larger than rbcs

have nuclei

less numerous

1% of blood volume

defend against invaders

produce antibodies

3 types of wbcs

granulocytes - most abundant

lymphocytes

moncytes

3 types of granulocytes

basophils

eosinophils

neutrophils

thrombocytes

platelets

small pieces of cytoplasm

lack nuclei

more abundant than wbc

process of coagulation

complete blood count cbc

common test that measures the number of rbcs, wbcs, platelets, and hemoglobin

volume of rbc in whole blood (hemotocrit)

erthrocytosis

high levels of rbcs

caused by smoking, high altitudes, dehydration

anemia

low levels of rbcs

due to huge blood loss, vitamin deficiency, infections, sickle cell

leukocytosis

high wbcs

show signs of infections, allergies, bone marrow disease

leukopenia

low levels of wbs

result from lead poisoning, infection, anticancer,

antigens

surface proteins on rbc

determine a person’s blood type

if blood from a person with a differing antigens is placed, the immune system can attach these rbcs and destroy them

agglutionation

clumping up do to the presence of different antigens

antibody protein will bind to more than one antigen protein leading to clumping up

antigen antibody complex

antigens immobilized and clumped up

caused by aggultination

antibody

immunoglobin

immune system produces this in the plasma for the antigen not present

some cases already present

some cases needs to be introduced

type a blood

antigen a on rbcs

antibody b in plasma

type b

antigen b on rbcs

antibody a in plasma

type ab

both antigen a and b on rbcs

no antibodies in plasma

type o

neither antigens a or b on rbcs

both a and b antibodies in plasma

rh factor

another antigen found on surfaced of rbcs

yes antigen — rh+

no antigen — rh -

to produce rh antibody requires exposure to the antibody

antiserum

needed for blood typing

blood that contains specific antibodies