Life exam 3

Cellular asexual reproduction

daughter cells are identical copies of mother cell

Cellular sexual reproduction

daughter cells are not identical copies of mother cell

Sexual reproduction occurs only in____ and asexual occurs in ________

eukaryotes, all organisms

Chromatin

DNA + proteins

Human genome has how many chromosomes

46

Genome

total cellular DNA

Centromere

connection between 2 chromatids

Components of the cell cycle

1. Cell growth

2. Mitosis

3. Cytokinesis

Interphase

Cell growth and copying of chromosomes

M-phase

Mitosis and cytokinesis

subphases of interphase

G1 phase

S phase

G2 phase

What happens in the S phase

Chromosomes are duplicated

Where does the miotic spindle occur

metaphase

What is the miotic spindle

a structure made of microtubules that controls chromosome movement during mitosis

Kinetochores

protein complexes associated with centromeres

Cytokinesis occurs by which process IN ANIMALS

cleavage by forming a cleavage furrow

Cytokinesis occurs by which process IN PLANTS

a cell plate forms

Cell cycle control system

checkpoints determine if the cell cycle stops if somethings wrong until a go-ahead signal is received

What is the most important cell checkpoint

G1

Why is G1 the most important checkpoint??

If a cell doesnt get the go-ahead signal, it goes into G0 phase

What is the G0 phase??

a non-dividing state

Where are all the cell checkpoints??

G1 checkpoint

G2 checkpoint

M checkpoint

What is density dependent inhibition

when crowded cells stop dividing

Genes

the units of heredity

What are genes made up of

segments of DNA

Gametes

Sperm and eggs

Human asexual reproduction

offspring are genetically identical to each other and to the parent cell

Human sexual reproduction

2 parents make an offspring that have unique combinations of genes inherited from BOTH parents

Diploid

2 copies of each chromosome (2n)

Haploid

1 copy of each chromosome (n)

Somatic cells

body cells

Gametes are ___ and somatic cells are ____

haploid, diploid

F1 generation

hybrid offspring of the P generation

homologous chromosomes

two chromosomes in each pair of chromosomes

Fertilization

the union of sperm and eggs

What is the fertilized egg called?

zygote

a zygote has one set of chromosomes from ____

each parent

Why does sexual reproduction occur??

more genetic variation

Independent assortment

when homologs orient randomly and are divided randomly into daughter cells in meiosis 1

Crossing over

when homologous portions of 2 nonsister chromatids trade places and pieces of DNA are exchanged

synapsis

when homologous chromosomes pair

Genetic traits

the physical properties of an organism determined by 1 or more genes

Locus

the location of a gene on a chromosome

Alleles

versions of a gene

Homologous genes

same locus on homologous chromosomes

How are genes given to offspring

gametes

Who is Gregor Mendel??

discovered the basic principles of heredity by breeding garden peas

P generation

true breeding parents

F2 generation

when F1 individuals self or cross pollinate with F1 hybrids

what ratio of purple to white flowers in F2 gen did mendel discover

3:1

Recessive alleles are ____ proteins

nonfunctional

dominant alleles are ____ proteins

functional

Punnett square

a diagram for predicting the results of a genetic cross between individuals

law of segregation

alleles for a specific trait will sepereate from each other during gamete formation

homozygous

2 identical alleles

heterozygous

two different alleles

law of independent assortment

alleles for one trait will segregate independently of alleles for a different trait

Incomplete dominance

phenotype is somewhere between the phenotype of the parents (red x white = pink)

Codominance

Heterozygotes show combined phenotype

polygenic inhereitance

an additive effect of two or more genes on a single phenotype

epistasis

a gene at one locus that alters the phenotypic expression of a gene at a second locus

example of polygenic inheritance

skin color

example of epistasis

labrador coats

Females chromosomes are

XX

Males chromosomes are

XY

Autosomes

chromosomes that arent sex chromosomes

how many genes do X and Y chromosomes contain

X contains most while Y contains very few

For a recessive x-linked trait to be expressed, females need ___ copies of the allele while males only need ___

two copies, one copy

Color blindness is much more common in

males

if a female is heterozygous for a particular gene located on the X chromosome, she will be a _____

mosaic for that character

Example of X inactivation

tortoiseshell cats

linked genes

genes on the same chromosome that tend to be inherited together

morgans experiment of linked genes

crossing flies that differed in body color and wing size

linked genes do not assort ___

independently

recombination frequency

the farther genes are apart on a chromosome, the more chance of crossing over

equation for recombination frequency

(number of recombinant offspring)/(total number of offspring) x 100

nondisjunction

when pairs of homologs do not seperate normally during meiosis

Aneuploidy

abrnormal number of a particular chromosome

example of aneuploidy

down syndrome (trisomy 21)

Polyploidy

extra copies of entire genome - LETHAL in humans