Bio Exam 3

gene

functional unit of DNA

genome

all of the DNA in a cell

chromatin

threadlike DNA/protein complex packaged in the nucleus of eukaryotic cells

chromosomes

tightly packed DNA molecules; occur as homologous pairs in some organisms

diploid

each chromosomes is paired; cells have two copies of every gene

haploid

only one chromosome of each pair is present; cells contain one copy of every gene

chromatin

complex of DNA and proteins (histones)

euchromatin

chromatin that is not tightly packed and can be easily expressed

heterchromatin

chromatin that is tightly packed and cannot be easily expressed

somatic cells

non-reproductive cells (diploid 2n)

homologous pairs

same genes

gametes

reproductive cells (haploid, n)

sister chromatid

duplicate chromosome made up of copies of a chromosome

The product of chromosome duplication is __________.

two chromatids

duplication

each chromosome has a homologous pair, each chromosome is duplicated (two sister chromatids)

diploidy

each chromosome has a homologous pair, each chromosome is not duplicated (no sister chromatids)

interphase consists of what 3 parts?

G1, S, G2

M phase includes ______ and _______.

mitosis and cytokinesis

mitosis

the division of genetic material

mitotic spindle

a bunch of microtubules of the cytoplasm

cytokinesis

the division of the cytoplasm

mitosis includes what 4 stages?

Prophase, Metaphase, Anaphase, Telophase

prophase

-chromosomes condense
-sister chromatids have been formed prior during the S phase
-centrosome containing two centrioles
-mitotic spindle begins to form
-nuclear envelope begins to break down

metaphase

-nuclear envelope breaks down completely
-some microtubules attach to the kinetochore proteins around the centromeres of the chromosomes
-other microtubules overlap with those from opposite pole and lengthen to push centromeres apart
-chromosomes are lined up on the metaphase plate

anaphase

-sister chromatids pulled apart opposite sides of cell
-spindle microtubules attached to kinetochores shorten while overlapping microtubules lengthen

telophase

-each new daughter cell has one centrosome
-each daughter cell has full genome of unduplicated chromosomes
-nuclear envelope begins to develop
-chromosomes starts to decondense
-cleavage furrow forms by microfilament action (cytokinesis)

What the G1 checkpoint?

does the cell want to divide?

What is the G2 checkpoint?

Are chromosome duplicated? Are there enough resources for two new daughter cells?

What is the M checkpoint?

Are all chromosomes lined up on the metaphase plate? Are all chromosomes attached to the mitotic spindle?

How do prokaryotes reproduce by?

binary fission

What occurs at the same time during binary fission?

S phase and mitosis

tumors

cells that divide too quickly

nucleosome

beads on a string of DNA

a duplicated chromosome is attached at the region called __________ where the sister chromatids connect

centromere

what occurs in the G1 phase?

growth, chromosome are diploid (linear)

what happen in the S phase?

DNA is synthesized, chromosome are duplicated, sister chromatids

What is anchorage dependence?

cells need a surface to grow on

What is density-dependent inhibition?

cell is constantly getting signals from cells, says don't divide, forms a single layer

heredity

the passing of traits from one generation to another through reproduction

trait

genetically determined characteristic coded by genes

gene

unit of heredity; physically located on DNA

allele

variations of a particular gene

locus

specific physical location on a chromosome

asexual reproduction

single individual passes genes from offspring to create clones

sexual reproduction

two parents give rise to offspring that have combinations of genes from both parents

gamete

cell that contains a single set of chromosome (haploid, n)

meiosis

creation of non-identical haploid gametes

In animals, fertilization produces zygotes and meiosis produces...

gametes

What occurs in meiosis I?

homologous pairs are separated (1 diploid cell forms 2 haploid cells with duplicated chromosomes)

What occurs in meiosis II?

sister chromatids are separated (2 haploid cells with duplicated chromosomes form 4 haploid cells with unduplicated chromosomes)

During metaphase I, what happens?

homologous chromosome pairs line up on the metaphase plate

During anaphase I, what happens?

homologous chromosome pairs are separated

no ? phase between meiosis I and meiosis II

S phase (duplication)

What is unique about prophase I in meiosis?

crossing over; homologous pairs physically connect and exchange genetic info

What is unique about metaphase I in meiosis?

pairs of homologous chromosome independently assort at the metaphase plate

What is unique about anaphase I in meiosis?

members of each homologous pair (not sister chromatids) separate from one another

independent-assortment

each pair of chromosome is sorted into daughter cells independently of other pairs

random fertilization

any sperm can fuse with any egg

tetrad

two homologous paired together (4 sister chromatid)

synapsis

process of homologous pairing together

chiasmata

point between non-sister chromatid that result in crossing over

plants and some algae can be...

diploid multicellular (sporophyte) or haploid multicellular (gametophyte)

fungi and protists can be...

only haploid multicellular or unicellular

Law of segregation

two alleles for a heritable character separate during gamete formation

phenotype

physical appearance or expression of a character

genotype

genetic makeup or combination of alleles

homozygous

two identical alleles for a gene

heterozygous

two different alleles for a gene

punnet squares

analyze the chances of producing different offspring from a cross of two known parental genotypes

Law of independent assortment

alleles for different genes assort independently from each during gamete formation

Degree of dominance

alleles are not completely dominant or recessive

Multiple alleles

a gene has more than two alleles

Pleiotropy

a single gene produces multiple phenotypes

Epistasis

one gene alters the expression of another gene

Polygenic inheritance

multiple genes affect the expression of one phenotype

Complete dominance

phenotypes of the heterozygous and homozygous dominant are identical

Incomplete dominance

phenotypes of the heterozygote is somewhere between the phenotypes of the homozygous dominant and homozygous recessive (blending)

Codominance

two dominant alleles affect the phenotype in separate ways

Chromosomal theory

genes have loci on chromosomes, chromosomes undergo segregation and independent assortment

Sex-linked gene

gene that is located on either sex chromosomes

SRY gene

on the Y chromosome that codes for a protein that directs the development of male anatomical features

hemizygous

only have 1 copy of chromosomes

linked genes

genes located on the same chromosome that tend to be inherited together

genetic recombination

shuffling of linked genes betweeen homologous chromosomes

what are the types of the chromosome breakage?

deletions, duplications, inversions, translocation

aneuploidy

extra or missing chromosomes; results from fertilization of gametes produced after nondisjunction

monosomy

a single copy of chromosome

trisomy

three copies (1 extra) of a chromosome

polyploidy

more than two complete sets of chromosomes

triploidy

three sets of chromosomes

tetraploidy

four sets of chromosomes

deletion

removes a chromosomal segment

inversion

reverse a segment with a chromosome

duplication

repeats a segment

translocation

moves a segment from one chromosome to a nonhomologous chromosome

klinefelter syndrome

XXY; result of an extra X chromosome in a male

turner syndrome

X0; result of missing X chromosome in females; usually sterile

down syndrome

trisomy 21; associated with many mental and physical developmental impairments

cri du chat

deletion in chromosome 5; results in mental retardation; individuals usually die in infancy or early childhood

chronic myelocytic leukemia

form of cancer caused by translocation between chromosomes 22 and 9; called the Philadelphia chromosome