Genetics Midterm

genes

segment of DNA that codes for a trait, unit of heredity

cells

Basic unit of life

genome

sum total of all an organisms genetic material (DNA)

alleles

gene variants, different versions of the same trait

karyotype

size order display of all an organisms chromosomes

genotype

combination of alleles inherited

phenotype

expression of alleles, organisms appearance

dominant

only need to inherit one copy to express this trait (AA or Aa)

recessive

must inherit two copies of all an organism's chromosomes

pedigree

diagram showing inheritance of trait through multiple generations

explain a prokaryotic cell

1. small and simple

2. no nucleus or membrane bound organelles

3. single circular chromosome

example: bacteria

explain a eukaryotic cell

1. larger more complex

2. DNA surrounded by a nucleus

3. multiple linear chromosomes

4. have membrane bound organelles that carry

example: plants and animals

nucleus

Control center, houses genetic material

Endoplasmic Reticulum

Synthesizes and transports proteins and lipids

golgi apperatus

Modifies, sorts, packages and transports proteins

lysosomes

Digests unwanted cellular material

Mitochondria

Converts energy in food to ATP

ribosomes

Makes proteins, found in cytoplasm and rough ER

plasma membrane

Regulates what enters and exits the cell

Cytoskeleton

Maintains cell shape, aids in cell movement

cell cycle diagram

all part of interphase

phases of mitosis

interphase, prophase, metaphase, anaphase, telophase (beggining of cytokinesis)

How many total chromosomes make up the human genome? How many are autosomes and how many are sex chromosomes?

humans have 46 chromosomes (23 pairs)

• autosomes: 44 chromosomes (22 pairs)

• sex chromosomes (1 pair)

What was the Human Genome Project? When did it take place and what was accomplished?

a research project to map and sequence the entire human genome.

• sequenced 3 billion pairs of DNA

• between 1990-2013

What is a stem cell? How do adult and embryonic cells differ and what are IPS cells?

a stem cell is an undifferenced cell that divides into specialized cell types

• adult: limited potential

• embryonic: unlimited potential

IPs cells induced pluripotent stem cells

How is the cell cycle regulated and what can happen if cell cycle regulation fails?

by check points and if they fail then uncontrolled cell division can occur

explain mitosis

1. produces 2 identical diploid, stomatic cells

2. growth/tissue repair

3. 1 division

explain meiosis

1. produces 4 unique, haploid gametes

2. gamete production

3. 2 divisions

explain spermatogenesis

1. one cell becomes primary spermatocyte

2. after division 2 haploid secondary spermatocytes

3. then that divides into 4 spermatids

explain oogenesis

1. formation of egg cells

2. diploid cell --> oognium

3. developes into primary oocyte

4. meosis 1 divides into secondary oocyte

homozygous

Two of the same alleles, AA or aa

Heterozygous

Two different alleles, Aa

Autosomal Dominant

Affected individuals are AA or Aa

Autosomal Recessive

Affected individuals are aa, carriers are Aa

Punnett Square

Determines the possible outcomes of genetic crosses

mendels 1 law

Law of Segregation: alleles will segregate into gametes during meiosis and unite randomly in fertilization

mendels 2 law

Law of Independent Assortment: inheriting an allele on one chromosome does not impact the chances of inheriting one chromosome

Differentiate between diploid and haploid cells.

diploid cells- (2n) contain two sets of chromosomes ex. stomatic cells

haploid cells- (n) contains one set of chromosome ex. gametes

What can occur during meiosis resulting in gametes with an incorrect number of chromosomes?

nondisjunction is when chromosomes fail to separate property during meiosis

Who is considered the father of genetics for his contribution to determining the mechanism of heredity?

Gregor Mendal

Differentiate between an organism's genotype and phenotype.

genotype: genetic makeup of an organism (AA, aa)

phenotype: the physical traits of an organism by the genotype

Lethal alleles

Alleles that when inherited together result in death

Multiple alleles

More than 2 just alleles exist for a trait

Epistasis

One gene affects the expression of another gene

Pleiotropy

Single gene mutation has many effects on an individual

Incomplete penetrance

Inheriting the genotype, but not having the phenotype

Variable expressivity

Expression of the same alleles can vary in individuals

Phenocopy

Environmental trait that appears to be inherited

Genetic heterogeneity

Single phenotype can be caused by many different genes

Incomplete dominance

Heterozygous are a blending of both alleles

Codominance

Dominant alleles both expressed in heterozygotes

complete dominance

AA or Aa - dominant allele

aa - recessive allele

incomplete dominance

AA

AB - blend of 2 other pheonotypes

BB

codominance

AB

AB - both alleles A and B expressed

AB

Phenotype: type A

Genotype:

I^A I^A or I^Ai

Phenotype: type B

Genotype:

I^B I^B or I^Bi

Phenotype: type AB

Genotype:

I^A I^B

Phenotype: type O

Genotype:

ii

Heterogametic

In humans, it is males, two different sex chromosomes

X-linked Trait

Trait that cannot be passed on from father to son

Y-linked Trait

Trait that is only passed from father to son

Y Chromosome

Chromosome only found in males

Hemizygous

Males for X-linked traits, only one X chromosome

Homogametic

In humans it is females, two of the same sex chromosomes

Pedigree

Chart that shows the inheritance of a particular trait

X Chromosome

Chromosome found in both males and females