Does a straight beat three of a kind?

Yes. A straight is rarer than three of a kind as a five-card hand, so it ranks higher. With seven cards the two are almost equally likely, but the official order stays the same.

Is A-2-3-4-5 a straight?

Yes. It is the lowest straight, called "the wheel". The Ace counts as one.

Rank 6 of 10

Straight

Five cards in sequence, of mixed suits.

Chance in Hold'em (7 cards): 4.62%
Odds against: 20.6 to 1
Chance in 5 cards: 0.3925%
Five-card combinations: 10,200

The highest card in the straight decides who wins. The top straight is A-K-Q-J-T ("Broadway") and the lowest is 5-4-3-2-A ("the wheel").

Straights are made from draws: an open-ended straight draw has 8 outs, a gutshot has 4.

Beats: Three of a Kind and everything below.

Questions players ask

Does a straight beat three of a kind?: Yes. A straight is rarer than three of a kind as a five-card hand, so it ranks higher. With seven cards the two are almost equally likely, but the official order stays the same.
Is A-2-3-4-5 a straight?: Yes. It is the lowest straight, called "the wheel". The Ace counts as one.