Biology Term 3 Topic Test

Biology Terms and Definitions

Features of an AUTOSOMAL DOMINANT Pedigree

• all affected have at least 1 affected parent

• once the trait disappears in a branch it does not reappear

• equals males and females

Features of an AUTOSOMAL RECESSIVE Pedigree

• two unaffected parents can have an affected child

• all children of two people with the condition must have the condition

• a trait may disappear in a branch and reappear

• equal males and females

Features of an X-LINKED DOMINANT Pedigree

• a male with the trait gives it to all daughters no sons

• female with trait may give it to all genders

• all affected have at least 1 parent with the trait

• if the trait disappears from a branch it doesn’t reappear

• more affected females than males

Features of an X-LINKED RECESSIVE Pedigree

• all the sons of a female with the trait are affected

• a pattern can be: aft. male → non aft. daughter → aft. male

• all children of two people with the trait will show the trait

• more males than females

What are the blood types?

A, B, AB, or O(i)

What are inorganic molecules?

Molecules that are relatively small and usually do not contain carbon, e.g. water, oxygen gas, carbon dioxide, minerals, vitamins

What are organic molecules + examples?

Molecules that are relatively large and carbon-based, e.g. carbohydrates, lipids, fats, proteins, nucleic acids. These are macromolecules.

What are polymers?

macromolecules are polymers, meaning that they are made up of many repeating subunits that are similar or identical to each other.

What is the monomer of carbohydrates?

Monosaccharide

What is the monomer of lipids?

fatty acids and glycerol

What is the monomer of protein?

amino acid (20 diff types)

What is the monomer of nucleic acid?

nucleotide (stores biological information)

What is the backbone of a DNA strand?

Phosphate

What are the four nitrogenous bases in a DNA strand?

adenine, guanine, cytosine, thymine

What is the cell membrane made of?

2 Phospholipids with a hydrophilic head and hydrophobic tail

What does a nucleotide contain?

• phosphate

• pentose suger

• nitrogenous base

What is the difference between RNA and DNA nucleotides?

The RNA nucleotide has ribose as the sugar, while DNA has deoxyribose (RNA also uses Uracil instead of Thymine)

What is RNA?

RNA contains the coded instructions that ribosomes use to build proteins (single stranded)

What is a chromosome

A strand of DNA that is coiled around histones

What are homologous chromosomes?

• pair of chromosomes

• same size and shape

• one of each from both parents

What is a gene?

A section of a chromosome that codes for making a protein

What are alleles?

Different forms of the same gene

What is a genotype?

The genetic coding of an individual trait

What is a phenotype?

The physical expression of the genes/proteins that are produced

What does homozygous mean?

Possessing the same alleles for a given characteristic

What does heterozygous mean?

Possessing different alleles for a given characteristic

What is incomplete dominance?

When two parent’s phenotypes blend to create a new phenotype (one allele is not completely dominant over the other)

What is codominance?

When two parent phenotypes are expressed together in their offspring (neither are dominant or recessive)

How many chromosomes are in human eggs or sperm?

23

What do centrioles do during cell division?

They use spindle fibres to separate chromosomes at the equator of the cell

Explain the four steps of mitosis?

• Prophase: Chromosomes condense, and spindle fibres begin to form

• Metaphase: Chromosomes align in the cell's equator

• Anaphase: Chromosomes are pulled apart to opposite sides

• Telophase: Nuclear membranes reform around the separated chromosomes

Explain the steps of meiosis - stage one

• Prophase I: Chromosomes condense, pair up, and exchange genetic material (crossing over)

• Metaphase I: Homologous chromosome pairs align in the centre

• Anaphase I: Homologous chromosomes are pulled to opposite sides

• Telophase I: Two new cells form, each with half the original chromosome number

Explain the steps of meiosis - stage two

1. Prophase II: Chromosomes condense again in the two cells

2. Metaphase II: Chromosomes align in the centre of each cell

3. Anaphase II: Sister chromatids are pulled apart to opposite sides

4. Telophase II: Four genetically unique cells are formed, each with half the original chromosome number

What does it mean if a gamete has a haploid number of chromosomes?

It has half the number, or one set, of chromosomes in a regular (diploid) cell

What does it mean if a gamete has a diploid number of chromosomes?

It has the total number of chromosomes, or two sets, one from each parent

What is the acronym to remember the phases of cell division?

PMAT:

• prophase

• metaphase

• anaphase

• telophase

What is the difference between stage I and II of meiosis?

In stage I the chromosomes condense in homologous pairs and separate into one chromosome, and in stage II they separate into two chromatids

Outline what happens in the prophase of mitosis

• centrioles migrate to the poles of the cell and produce spindle fibres

• nuclear membrane breaks down

• chromosomes condense and become visible in cytoplasm

• chromosomes migrate to the equator of the cell

Outline what happens in the metaphase of mitosis

• chromosomes line up at the equator head-to-toe

• spindle fibres attach to the centromere of each chromosome

Outline what happens in the anaphase of mitosis

• spindle fibres contract towards the centrioles

• the chromatids are pulled apart towards opposite poles of the cell

Outline what happens in the telophase of mitosis

• new nuclear membranes form around each group of chromosomes

• spindle fibres break down

• the cell membrane and cytoplasm splits into two cells

Interphase

Where DNA replication occurs

What is the outcome of mitosis

Two diploid daughter cells that are genetically identical to the parent cell are produced.

Location of cell division in multicellular organisms

In all body tissues - somatic cells

DNA Replication

• produces copies of each chromosomes called chromatids

• they are connected at the centromere to form double stranded chromosomes

• doubles the amount of DNA in the nucleus to maintain diploid number over cell division

Transcription

The process of making a copy of the genetic codes in the DNA onto an mRNA

Where does transcription occur

The nucleus of the cell

Transcription requires:

• free nucleotides to build the mRNA (A, U, G, C)

• RNA polymerase that builds the mRNA molecule

What does RNA polymerase do?

Unravels and unzips the DNA and builds a molecule that is complementary to the DNA sequence

Translation

The process by which the genetic code on the mRNA is used as a blue print to make protein

Where does translation occur?

The ribosome of the cell