cell cycle, chromosomes, and meiosis

gene

short section of a string of DNA that influences a trait

genome

whole genetic info of an organism with the entire nucleotide sequence

chromosome

a threadlike strand of DNA in the cell nucleus that carries many genes

DNA

a double helix molecule made of two antiparallel strands of nucleotides linked by hydrogen bonding between complementary base pairs

mitosis

cell division in which the nucleus divides into nuclei containing the same number of chromosomes

meiosis

cell division that produces reproductive cells in sexually reproducing organisms

prophase

DNA condenses into chromosomes, spindle fibers built, nuclear membrane breaks down and centrioles move towards poles

metaphase

spindle fibers attach to centromeres and chromosomes align on equator

anaphase

spindle fibers shorter, sister chromatids split into identical chromosomes and chromosomes are pulled to poles

telophase

chromosomes unwind, spindle fibers break down, nuclear membrane reforms two identical nuclei

cytokinesis

the division of the cytoplasm in two that may occur after telophase

cyclins

proteins whos concentration controls parts of cell cycle and found in all eukaryotes that activate cyclin dependent kinases

pancreatic exocrine cells

copy all chromosomes, build ribosomes, multiply mitochondria, transcribe and translate selected genes and carry out functions

palisade mesophyll cells

copy all chromosomes, build ribosomes, multiply mitochondria and chloroplast , transcribe and translate selected genes and carry out functions

cancer

repeated rapid divisions that ignore growth inhibitors that creates out of control cell growing

mutagens

agents that cause mutations in DNA (radiation, free radicals, chemicals, viruses)

oncogens

overexpressed proto-oncogens, genes that influence cell cycle and lead to cancer, have alleles that make cancer more likely

proto-oncogens

normal state of oncogens

treatment of cancer

radiation + chemo (causes damage to intestine because they are also rapidly dividing cells)

codons

mRNA that carry messages in groups of 3 nucleotide bases

structure of RNA

4 nitrogenous bases (A, U, C, G) with 64 possible codons + 20 amino acids

proteins

amino acids assembled using RNA instructions to produce needed proteins

sickle cell anemia (description)

a base substitution mutation created the sickle cell allele (HbS) from standard allele (HbA), 1N base is changed (RNA: GUG --> GAG)

hemoglobin

100s of millions of proteins in 1 rbc that carry oxygen

sickle cell anemia (hemoglobin)

146 codons in B hemoglobin and the 6th is mutated (glutamic acid to valine) causing hemoglobin to polymerize + twisting shape of rbc

cairn's autodiography to estimate DNA length

grow cells with 3H in thymine (radioactive) bc its the only one not in RNA, Beta radiation (electrons) from DNA react with photo film

karyograms

way to view a eukaryotic cells chromosomes

what happens in meiosis

one diploid nucleus divides into 4 haploid nuclei which reduces the chromosome number by half and allows sexual life cycle by fertilization

interphase

DNA is replicated and cell carries out function

prophase I

homologous chromosomes pair up, crossing over + DNA condenses into X shapes

metaphase I

chromosomes align in pairs on equator w/ spindle fibers,

anaphase I

spindle fibers shorter pulling chromosomes to poles, sisters go to the same pole (where nondisjunction is possible)

interphase II

rest period + centriole replication

prophase II

chromosomes condense + nuclear envelope breaks down

metaphase II

chromosomes align on equator

anaphase II

spindles shorten sister chromatids to poles

telophase II

nuclear envelope reforms + DNA unwinds

crossing over

occurs in prophase I, equivalent pieces of DNA from non-sister chromatids is traded and 4 chromatids line up (synapsis), cuts made at same DNA location + non-sister strands attached for allele exchange

random orientation

allow for independent assortment of genes

nondisjunction

happens in anaphase when spindles dont sep[erate leading to an atypical chromosome number

chiasma

places where homologous non-sister chromatids connect + crossover coordinated by proteins

cells obtained for karyotyping

cells in metaphase necessary

amniocentesis

amniotic fluid extraction by hypodermic needle in abdomen, uterus and amniotic sac, fetal cells separated from fluid and cultured after 15 weeks, infection levels range from 0.7 to 1%

chorionic villus sampling

chorionic villi (pre-placenta) pulled out through vagina or needle in abdomen at 10 weeks, risk of infection is 1-2%

increased parental age leads to?

increased risk of non-disjunction

RNA

G, U, A, C

proteome

the full complement of proteins produced by a particular genome

autosomes

one of the numbered chromosomes

genotype

the description of all alleles an individual may have

what are the features of bacterial genetic material?

not associated with proteins, and consists of a DNA loop with a single copy of each gene.l

locus

the specific site of a particular gene on its chromosome

what is tetrad made up of?

two homologous chromosomes

synapsis

the pairing of two chromosomes that occurs during meiosis

bivalent

one pair of chromosomes (sister chromatids) in a tetrad.

when do chiasmata form in meiosis?

prophase I